Apple snails have many different names in the trades, so it gets confusing.
There are different species of apple snails, some will eat plants. The plant safe species I know of is Pomacea bridgesii. this is referred to as Inca snails in some lfs.
However, most lfs cannot identify the snails by species. <I once got some P. cannuliculatas sold as bridgesii .... well, canas are voracious plant eaters.>
The differences in appearance of the various apple snails are subtle. Go to applesnail.net to learn to ID the snails. Most lfs don't know what they are selling, so they call them "mystery snails" ... ie. It is a mystery what you are getting!