What is the difference between a contract, deed and a covenant?
A contract is an agreement legally enforceable against at least two people, in writing or otherwise.
A deed is a formal document conveying an interest in real property from one party to another.
A covenant is most typically going to refer to a condition that is part of either of those transactions, such as a contractual covenant not to compete or a deed covenant to use property in a certain way.
You may want to search for these words in the Black's Law Dictionary. That legal dictionary is a very useful starting point for when one needs to do legal research.
After reading the definitions, feel free to ask about any specific details that might remain unclear to you.