I know that may be this present question can show a little bit of naivety and the answer can be somehow obvious and trivial, but since I'm not sure about these issues, I'll be asking it anyway. Are celebrities subject to the same laws as poor people such as, let's say, not paying taxes or any other equal-level crime?
Are celebrities subject to the same laws as poor people such as, let's say, not paying taxes or any other equal-level crime?
Yes. Sometimes laws are enforced less harshly as a matter of law enforcement, prosecutorial and judicial discretion against the rich, famous and powerful, than the poor, but they are subject to the same laws and the authorities have the same power to enforce those laws against a celebrity or other rich or powerful person, as they do against anyone else.
Most criminal laws provide that factors such as whether someone is gainfully employed, whether they pay restitution for an offense, and whether someone has otherwise good character and be considered as grounds for leniency in sentencing someone for a crime of which that person is convicted, so that can systemically benefit such people at sentencing.
Also, the famous, rich and powerful may be seen as particularly credible in a trial by jurors.
They may be able to afford and support highly competent and exhaustively thorough legal representation, while the poor often get an overworked public defender with very little time or resources to devote to their case, or only a very inexpensive private criminal defense lawyer who similarly has limited resources and is rarely the most highly competent person in the field.
Similarly, the rich and famous can typically more easily be released on bail or on a personal recognizance bond pending trial, and being at large, rather than in jail, prior to being convicted, greatly reduces the pressure to plead guilty, the harm caused by the charge if there is an acquittal, and the ability of the defendant to mount a defense to a charge.
But, that doesn't change the fact that the same law applies to everyone, although this too has some bias inherent in it, as this famous aphorism illustrates:
The law, in its majestic equality, forbids the rich as well as the poor to sleep under bridges, to beg in the streets, and to steal bread.
-- Anatole France (16 April 1844 – 12 October 1924), born Jacques Anatole François Thibault, a French poet, journalist, and novelist, in Le Lys Rouge [The Red Lily] (1894), ch. 7 (In the original French, the quote is "La majestueuse égalité des lois, qui interdit au riche comme au pauvre de coucher sous les ponts, de mendier dans les rues et de voler du pain.").
Anatole France's point is true for somewhat deeper than the somewhat flip expression of the idea in this famous quotation suggests.
As a general rule, economic harms to others that people who cause them can usually remedy by actually being able to pay money as a result of a judgment in a civil lawsuit, are usually not defined as crimes. For them, the threat of a civil lawsuit is a sufficient incentive to modify their behavior.
In contrast, economic harms to other that the people who cause them usually lack the ability to remedy by paying money to someone who brings a civil lawsuit seeking a remedy for the harm, are often defined as crimes, because the threat of a civil lawsuit does not adequately deter their economically harmful conduct.
Likewise, one of the reasons that authorities choose to pursue a matter with criminal charges rather than leaving it to the people involved as a civil matter is the reality in cases where charges are brought that a civil lawsuit would be a futile means to attempt to punish a defendant for clearly improper conduct that harms others.
NOTE: While I have been very critical of the initial wording of the OP, since the ammended version is acceptable and the poster has not reverted the edition, I will try to answer it.
In general, in most Western countries, the law is equal for everybody1. But that does not mean that every criminal is equal. For the purpose of example let's use Cristiano Ronaldo (as you already mentioned him) and a bank robber.
The law: Obviously, not all the crimes are equal. CR's tax evasion is a crime that has some penalties set, the bank robbery is a different crime that has different penalties set. How these penalties are decided is a political issue, and it is not the judge's role to amend it even if he thinks them unfair2.
It is unlikely that CR will get caught robbing a bank (probably that is a net loss of income when compared with other activities) so the kind of crimes he is likely to commit is a different one, which will affect the legal consequences he risks.
Additionally, not all the legal codes are the same. In some countries tax fraud may be seen as less of a crime (or a "victimless crime") while in others it is a more serious offense. You cannot just compare the sentences among different countries3.
The crime: The bank robber enters a bank and openly performs a clearly illegal action. But a white collar crime like tax fraud does not happen openly: there will be attempts to disguise the crime as a legal operation. It does not even CR to actually perform the action, it can be ordered to some underlying, and there may be no single action that is illegal per se but just its combination.
As a result, once the bank robber has been identified and evidence collected the case is rather straightforward, but in the white collar crime it can be difficult to establish even that a crime has happened at all, not to mention who is actually responsible for it. This gives an incentive to prosecution to reach a settlement4
The means: The bank robber probably will have to do with some part-time lawyer (or just with overburdened free legal counsel), CR will have a team of top lawyers specialized in the crime he is accused for5. This is somewhat unavoidable unless you take away the accused freedom to chose their lawyers, which is a troubling proposition. Of course, this is another incentive for prosecutors to reach a settlement.
In short, to answer your question, celebrities are under the same legal system than common people. But if you want to compare their sentences to common people's one, you have to do some fine tuning to adjust for the kind of crime that a celebrity is likely to commit.
All of the above does not mean that the legal system is impervious to social influences. The legal system runs on persons, and persons do have a mind, prejudices and quirks6. It would be naive on my side to claim that someone's public status would never affect anyone involved in the legal proceedings; but the laws applying to them are the same.
But the celebrity status may be a double edged sword: it may also attract public attention and force prosecution and judges to show a harsher stance7.
1 There are some exceptions that may affect elected officials and heads of state, but those are counted and most times only mean that some extra steps may be necessary before a trial begins.
2 If you wonder why the legal code is "harsher" with the bank robber than with the tax evader, then you have a question for https://politics.stackexchange.com.
3 As I commented earlier, that a two year sentence for a first offender gets suspended/commuted into a fine is not that unusual in Spain.
4 And remember that in that a tax fraud case it means that the state recovers the money that it was earned plus fines and interests.
5 If that bothers you, remember that CR also has access to more and probably better doctors.
6 You can find some notorious examples in some sentences related to the Civil Rights of black people in Southern USA. Not that they are the only examples or the worst, but they are rather well publicited.
7 For what is worth, I did read some news about an association of tax collection personnel claiming that CR had had it easy when compared with a similar case that involver F.C.Barcelona's Lionel Messi. But:
Lionel Messi was not jailed either and the charge was that CR's fine should have been higher.
This reinforces my point that the accused celebrity can work against him, by inviting a higher level of scrutiny by the mass media/public.