>>127635054
a synth is an electronic sound sampler that you can both program or play around with
think of a mellotron, which is a proto-synthethizer: it's a keyboard instrument, but each key makes the sound of anything you pre-program it to make; woodwinds, strings, a full orchestra...
still, you can play around with it just like you would on any keyboard instrument
you can also just plug an electric guitar on a synth or any number of pedals, and it's still a guitar