As Maley already said, it's a very common meat product in Europe.
I don't eat it though, because I believe horses are elegant and beautiful creatures. But most people do eat horse meat and really like it. I principally never did, so I can't judge about the taste.
The difference in between cows and horses are obvious, cows are reproduced to slaughter (at least in Europe they are), and horse meat is only used when the horse it old, and when they can't use it anymore for hard labour, or to ride it.