It's a vague idea, really. But I've found very few electric bass players that swing if they don't also play upright.
Please note, "FEW", and not "NO". This thread is starting to sound a little defensive by some. This is my perpsective from my experience and isn't a matter of debate...just how I feel based on my experience and, no, I'm not feeling a need to rethink it. For whomever cares, here it is.
If they play upright, even if it's not as proficiently as they play electric, and we're playing a musical language that was written in the voice of the upright bass, then I want to hear upright. There are guys...like Kenny Davis whom I mentioned earlier...who can really swing hard enough on electric to make it feel great. But people like him are FEW and FAR between. And they are often adapting the way the play electric to make it feel more acoustic. More than TONE, they are changing the touch and space between the notes and where they put the notes in the beat to give it a more acoustic feel. It's something very few who don't also play DB reasonably well can do on electric bass.
That said, if you want to get into definitions of styles, I say leave that to the record companies and the people stuffing CD's in the bins at Sam Goody.
Fusion was a "for lack of a better term" word for years until someone decided it was a style. And then a lot of it started to suck. At some point jazz became "any music that didn't have words". And the music with no words that didn't have any improvisation became "new age" or "world music" if there were lots of drums in it.
I'm pretty sure you're supposed to play bridge pickup in fusion, and new age, but world music requires acoustic bass guitar to be authentic
I'm in the middle of rehearsals for a gig at Carnegie hall this weekend with the Baltimore Symphony. The show we're doing is a gospel version of Handel's Messiah, called "Too Hot to Handel". It's really pretty cool. There are 3 bass books. One orchestral book, one jazz DB book, and one EB book. In the past, they hired an acoustic player and an electric player. The past couple years they've hire me. Initially I was supposed to double since some of it is swinging....very jazz oriented. We discovered that the transitions were way too short for me to be able to switch, plus the stage was way too tight. So I played the whole thing on electric. And guess what...it was totally cool. The guy who wrote/arranged the music was using acoustic on the swinging stuff because that was what he heard. But in this case musicality trumped instrumentation and the EB did a satisfactory job for everyone.