To me, the major difference between the two is that North American slaves were generally treated better than the ones in Latin America. This was especially true after the slave trade was banned in 1808. North American slaves actually increased their numbers by natural increase (rather than by importation). By contrast, the slaves in Latin America were generally worked to death relatively quickly and did not live long enough to increase their population by reproducing.
Paradoxically, the Latin American colonies were actually less racist towards their slaves. There were more freed slaves and they were not really treated all that differently than the Indians were (and remember that Indians were a major part of the Latin American societies). This is very much in contrast to North America where there were relatively few free blacks and the blacks were treated very poorly.
The only major similarity is that slaves in both areas were slaves for life and any offspring they had would be slaves as well.