Assigning vs. selling an option?

What are the differences between:

You have a property under a sales contract and you assign it to another investor for an assigment fee,

versus

You have a property under option and you sell the option to another investor for a fee?

Thanks.

Howdy Chrisj:

A lot investors consider a sales contract the same as an option. Pretty much the only cure for default to perform is the loss of the earnest money. A contract you are supposed to close and an option you have the right but not the obligation. If you sell either you will get cash and have nothing else to do with the deal. From your point of view it would be the same.