Sharecroppers didn’t own the land they worked on, the tools they used, or the crops they harvested. They also weren’t paid a wage; they sold their crops to the landowner (often for deflated prices) while keeping a share (usually about 1/3 or 1/2) and were provided with lodging and some basic necessities. Additionally, most sharecroppers worked on what were formerly slave plantations, and it was the only viable form of employment for most former slaves.
Really, the only difference from slavery was the legal arrangement: they were tenants rather than chattel. That, and there were white sharecroppers as well as black, but the overwhelming majority were former slaves.
sharecropping: the landowners let the people live on their land and grow crop as long as they got a percentage of the crop to themselves
slavery: the landowners owned people who had to work for them and give them crop
the two are similar because the landowners still got crop/money even though they didn't have to work for it because they had other people working for them
