What is an "addendum to an agreement contract "?
Its just an additional set of terms that spell out (in more detail) the exact terms of the contract.
an addendum to the contract changes or adds to the conditions of the intially negotiated contract, like the intial contract it must be signed by both parties to be valid.
Addendums are supplements to the original contract at the time of signing. For example, a financing addendum give the buyer so many days to secure financing or an inspection addendum giving 10 days to have the property inspected. There are a number of addendums that can be added to the original contract before it is signed.
Amendments are like addendums except these take place after you have mutual acceptance. Amendments are changes to the original contract. For example, an extension to the closing date due to unforeseen circumstances. You are amending the original contract in this case.