I've had both and they seem similar to me, lol. I'm not saying they're the same thing. (I mentioned earlier that the closest North American equivalent to a crumpet is an English muffin.)
I'm apparently not alone in drawing the comparison:
<< The English muffin as it is known in the United States more closely resembles a crumpet than the muffin produced in Britain in that it has holes on the upper surface. In both cases this is due to the fact that a batter rather than a dough is used resulting in bubbles of gas, produced by the leaven, breaking the surface as the cake cooks. The muffin dough used in Britain is slightly firmer in texture preventing this from occurring. Other than moisture content, there is little difference between a muffin dough and a crumpet batter. >>
http://en.wikipedia.org/wiki/Muffin_(English)

