Plant-eaters: Eyes on sides of head (to spot predators).
Meat-eaters & humans: Eyes in front of head (to track prey).

Plant-eaters: make their own vitamin B-12.
Meat-eaters & humans: must get B-12 from animal products (even Vegans must do this or eventually perish).

Plant-eaters: restricted to temperate areas where plants are plentiful.
Meat-eaters & humans: can populate extremely cold environments as long as meat can be found there.