Getting technical
The two main differences between these types of amps are the size of the speakers and how the preamp works, so let’s take a look.
As we’ve already mentioned, a bass guitar generally produces lower frequencies. Consequently, bass amps will have a preamp stage which focuses on those low and aggressive tones, so the speaker vibration (or response) is more pronounced and stronger.
You will also find much bigger magnet in the speakers housed in a bass amp. These push air and help the sound resonate, producing a louder sound while being able to handle the more aggressive frequency response.
Guitar amps, on the other hand, have preamps that focus more on mid and high ranges. This, teamed with the thinner speakers, means that this is a much simpler and more direct process.
In summary, a simple preamp with a large speaker makes up bass amps. Whilst a complex preamp and smaller speaker make an electric guitar amp