They both created Silk Road.
Ross Ulbricht built Silk Road 1, and Blake built Silk Road 2.
Silk Road is a dark web app that allow people to buy drugs to US. The legality is complicated. I wonder if Ross is not an american citizen but say, a citizen where drug dealing is legal, then chance is he's not breaking any crime. The site it self is not in US and should not have been subject to US laws.
In any case they both got caught.
So why the difference in sentencing?
Note: I checked Could Ross Ulbricht from Silk Road not get life sentence?
That question totally do not answer this question.
I would give a bit of detail about the case that I know. Ross is convicted of the same crime with Blake. They did the exact same thing. I may be wrong here.
However, Ross is also "suspected" of hiring someone for murder. He is not "charged" with attempted murder. However, that "suspicion" is taken into account in his sentencing.
That, and many other possible factors, is what suspect may have played a part in Ross' sentencing.
However, I am not a legal expert. I wonder if any legal expert that are familiar with the case can shed some light.