Longevity doesn't necessarily require a mechanical expression, except for something like the age chart. But that still matters mechanically because if you say get aged by a ghost or something, then the longevity comes into play in a potentially significant way
Also, physical differences don't have to. They can be whatever the game wants (description, mechanics, etc). My point is just D&D loses something if races don't have mechanics to back up the physical differences (I think it runs into the humans in funny hats problem).
It can be both meta game and feel. Those bonuses, special abilities etc are concrete things that add to the feel of playing a particular race