I was told that hares had long hind legs, while rabbits did not. But the Belgian Hare I once owned had long hind legs.
I remember also hearing that rabbits do no live in holes.
Now I hesitate to believe that.Help!

Well, one thing I know is that they are sufficiently different that the Rabbit Hemorrhagic Virus introduced here to control a Plague of rabbits had absolutely no effect on hares, while killing around 60-70% of the rabbits.

Dear Max: When I was in Public Health back in the fifties,
Australia was claiming over 90%. And they were using a bacterial agent whose name I can't now remember alternately.
I got a chuckle out of stories about sportmen moaning about being deprived of hunting when it got loose in UK. Almost immediately it became clear that the trees were doing better. Gotta see if I can find info about that virus/bacterium pair. It may be too old for Internet.

Edit: the virus of fifty years ago was myxoma virus.
Presumably rabbits must have developed resistance. I couldn't find any mention of the bacterial disease.

Yes, myxie was used here to, but it made a very ugly mess of the rabbits it killed, and was abandoned as inhumane.

Dear Max: strange that I cannot find the name of the bacteria that were used alternately with the myxoma virus.
The idea was that the virus would kill 90% of the rabbits,
and then the bacterial disease the next year would kill many of the ones that survived the myxoma virus. A one-two punch that sounded very promising. And the best thing was that there seemed to be no problem of their spreading to either humans or other animals. I got a very big chuckle out of early attempts, with "rabbiters" who released pregnant rabbit does so their job would never end.

hares had long hind legs … the Belgian Hare I once owned had long hind legs.

???

I forgot to mention, Mencken says Belgian hares are actually rabbits, and so do not have long legs. But mine had long legs.