As a general rule, the differences between grasshoppers, groundhoppers and crickets are:
1. the antennae of grasshoppers and groundhoppers are shorter than their bodies.
2. the collar (known as the pronotum) just behind the head of grasshoppers is short and saddle-shaped, but is much longer (in fact, as long or longer than the body) in groundhoppers.
3. the antennae of crickets are generally longer than their bodies (the exception is the mole-crickets)3.
Many grasshoppers and crickets are able to make a song that is specific to their species. Grasshoppers and groundhoppers make this sound by rubbing their legs and wings against each other. Crickets, bush-crickets and mole-crickets do it by rubbing their fore-wings together. Scientists call this 'singing' stridulating4.