My reds typically outlay the black. Not by much, but noticeable. Red seem more oriented toward people. Blacks were larger birds and seemed more cold hardy. Not surprising, since they have Barred Rock in them. Black also must sustain the larger size with slightly more feed intake.
There are sooooo many "custom blends" of these, blacks and especially the reds. The reds tend toward their RIR parentage while the blacks tend to favor either their Barred Rock parentage or Australorp, if that is what was used. Solid egg layers all and that's what's important because that was the objective of the breeding program that creates them.