A similarity between slavery and sharecropping was that

Sharecropping is when anyone lives and/or works on land that is not theirs and in return for their effort they pay no bills. Slaves pretty much did the same thing accept for the fact that they were the property of the land owner, without the choice of weather they wanted to work or not. Sharecroppers could decide they didn't want to do it any more and leave, slaves couldn't. The difference between the two is freedom, sharecroppers where free people, slaves were not.