OK! Let's just all agree that there is a distincion between different types of Bass! Let's list them. 
Acoustic-not amplifiable
Electric-more like a guitar, amplifiable
Upright Electric-amplifiable, upright, taller
Upright-upright, taller
double-depends, deeper or 2 necks
String types
3 stringer-one string taken away
4 stringer-basic bass
5 stringer-higher or lower string added(usually lower)
Now can we just agree that there are lots of different stringed instruments? Yes? good. Signed,