Two words: Buck Owens.
It's a little rougher around the edges than mainstream Nashville country of the early 60s (that's when the Bakersfield sound was established). The instrumental focus is more on the electric guitar, while Nasvhille country focused more on the pedal steel and fiddle for fills.
I'm not positive about this, but I think that before the Bakersfield sound was established, the most common guitar sounds in country music were Gibson hollowbodies. Thanks, in part, to Don Rich, the solidbody sound became more prevalent.