Re: Overdrive vs tube screamer?
Well said Soulcrusher.
Overdrive is overdrive, and Tube Screamer is an iconic style of overdrive. And it's a continuum - there is no hard / fast line between boost, OD, and Distortion. Names can be deceiving. Some units can just gradually shift from one to the other, some have switches. My Catalinbread Super Charged Over Drive - definitely does Distortion, but can drop down to OD land.
They will all give you:
warmer or brighter sound
More/Less mid boost
More less volume
More less dirt
The EQ options will vary in number and range.
I personally dig a Tube Screamer with my Fender Pro Jr. But the Junior is a bright fender style amp. That's probably why I dig the screamer. I also like the mid push. Many don't.
The BAd Monkey and Green Rhino are great examples of "more" and more flexible Screamer styles. Also, the DX-9 Turbo Screamer gives multiple setting for more, more and even more gain, and varying amounts of bottom.
Don't forget - interaction with the amp can be very important. MAny/Most OD's are intended to drive the preamp hard, as opposed to a distortion, which often provides the main dirt sound. But you can use the box as the sole source of the dirt.