I think that whippets are effectively mini greyhounds, although I should add that I've never owned a greyhound and the only ones I've come into contact with are ex racers. Whippets used to be called the poor man's greyhound, as they were bred for racing in the alleys between terraced houses, whereas greyhounds were owned by the wealthy.
I should point out (in the interests of full disclosure) that they can be quite crazy - Stanley was very chewy as puppy, and had (still has) moments of complete barminess, when he just runs round the house like a loon. But it doesn't last long and then he's crashed on the sofa again. Whippets don't do floors - they're too bony for that and they need to be kept warm at night (embarrassed to admit that ours sleeps in (not on!) our bed 
, but he makes a very effective hot water bottle 
).
He has a very strong prey drive - the only time his recall goes to pot is when he's stalking a squirrel!
Ours is unusual in that he does bark at passersby, but I understand that is unusual in a whippet (and I'm sure could be trained out of him). You can't leave anything out within his reach in the kitchen either.
But he is so loving and beautiful - currently curled up beside me on the sofa, cuddling his teddy, which he got out of his toybox himself. He'll put his head on my lap in a minute, which makes it challenging to type .