Generally speaking, Astrea snails are more pointy and look more like a true cone:
While turbo snails are usually larger and have a more rounded shape:
As far as their eating/grazing habits, in my experience they are very similar. They like the glass and will eat most algaes and diatoms. They are hit and miss when it comes to hair and cyano algae though. They are not detritus or carrion eaters, pretty much wholly herbivorous.