What exactly is the difference between apple snails and other snails, and how do I tell them apart?

Also, to those of you who have them, do you actually notice a difference algae-wise when you get one?

Thanks,
Aqua

Aqua, mine are pretty lazy when it comes to cleaning off algae. Only one out of the 8 I got I see actually doing some cleaning work.
As for differences, I think its mostly the size of them, they can get pretty big, especially the regular brown apple snail, the golden and blacks stay a little smaller. They also have a very unique breathing organ, a little antenna like thing that can extend, so they can stay under the water surface, and can take in air with that antenna. No other kind of snail has that.
Except for the apple snail, the mystery snail (which is actually a kind of a apple snail as well) and two or so other kinds of snail are considered pest snails. Those guys I wouldn't wonna have lose in any tank or pond, they take pretty much over!....

Apple snails are lazy for cleaning algae,but let them see a beautiful planted tank,and they'll give you a run for your money-100 yard dash in 2.2 seconds!

I only have on apple snail I’ve had him a couple of weeks now. I leave the algae cleaning to my hillstream loach the apple snail is much happier with some spinach, cucumber or if he’s quick enough the goldfish food.

nope my snail(s) are pretty lazy but make great pets.