distortion and overdrive is kinda different creature..both are distorted sound but as it said, overdrive is originally come when you play with max volume greater than the amp can hold, then the sound got distorted. distortion is originally guitar effect creating distorted sound.
simple saying, overdrive is not as harsh as distortion. I don't know for sure but to get max from you tube amp, you have to play it loudly to reach the great overdrive sound.
simple saying, overdrive is not as harsh as distortion. I don't know for sure but to get max from you tube amp, you have to play it loudly to reach the great overdrive sound.