Why did slaves have different experiences of working on plantations?

because slaves had masters whose personality was kinder or more mean than others

I'm not sure if this is 100% true, but its probably because slaves had less harsh daily work compared to other slaves because of their connection to the slave owner or if they were lighter skinned. I heard that light skinned slaves were better treated (but still suffered of course) but had less harsh works and were sent to clean the houses. I'm not 100% sure about this though