What bass is better a dean pro 4 string or an ibanez btb450qm if you like to play jazz and gospel?

also how can you tell if a bass is for rock or for jazz

A bass can be use for any type of music you choose...
I don't think there are any designes specifically for 'rock', 'gospel', or the like...
It may look a little strange if you showed up to play with the church choir on Sunday morning with a really radical body design, though!
Personally, I play (and prefer) the Ibanez BTB series...
They offer a really wide tonal range, and are suitable to ANY kind of music!
Cheers!
Bobby

The Ibanez is built more for jazz, but the Dean is a nice, dependable guitar. I'd go with the Ibanez, but either would work.

There's only one company for me when it comes to basses, Fender. They have a great reputation and make very reliable products. There are two basses Fender makes specifically designed for jazz and rock. One of these basses is called the Fender Jazz or "J" bass, the other is called the Fender Precision or "P" bass. Both are great basses that have been around for a long time, if you're considering buying a new bass definitely check both of them out.

I'm with "Drumwonder," I've been a Fender (J/P/and P Fretless)
for years. Still have my 64 Jazz which I bought new (with Dad's help) - LOL.

However, my Fender "commercial" doesn't answer your question. I have a couple of students that use both the Dean and the BTB....I, personally prefer the Ibanez. The Ibanez has more tone variation and appears "at a glance" to be built sturdier.

As far as which brand works best for which genre of music.........it's far more about string choice and amplification (inc. tone settings of each) than it is about brand.

Again, if you want a virtual "universal" Bass - take a good look at Fender. If cost is an issue (as it always is) take a look at their Mexican line.......good instrument at a very fair price.

And most of all - Good Luck to 'ya no matter what you choose.