I've heard enough people mistake these three terms, including television analysts, to feel compelled to write a little blurb about the differences between the three.
An end around is a handoff to a wide receiver from the quarterback. The END comes AROUND to get the ball from the quarterback. No running back is involved in an end around.
A reverse is a pitch or handoff to a running back who runs out to the edge and hands off to a wide receiver coming around. The ball REVERSEs direction. The rare double reverse is when the ball goes from running back to wide receiver to the other wide receiver. The ball REVERSEs twice, or DOUBLE the number of times as in a regular reverse.
It may seem simple, but plenty of people get it wrong. So if you hear some one incorrectly describe these plays, correct them in a tactful manner. And hopefully, someday, we'll live in a world where everyone knows the difference between end arounds, reverses, and double reverses.