RES generally get a little bigger than BG assuming enough food. They taste like BG. The RES can be a food source but they are much more easily overfished than BG because of reduced reproductive ability and limited pond ability to grow them (small niche in the pond for RES). RES are specialists (snails , worms , crustaceans , and some fish) unlike BG which are generalists (eat everything that fits in their mouth).