When these types of "artistic differences" crop up in band-land, it can be a difficult situation at the best of times for all involved, and inevitably it will come to a head if not sorted out soon. But there are one or two approaches you can take to solve this problem.
In my musical experience, artistic differences are a part of the landscape for all us musicians, and it's part of the magic and musical journey we all undertake when we pickup that first instrument and decide "I'm gonna be a musician yippee!". It's a common part of the process. Ignoring an issue like this won't work obviously as you have already sussed, and it will take it's course in the end with sometimes nasty results and friendships lost and so on. The good news here is that this can be easily avoided though. One thing is sure in my opinion and I hope it helps you out - this issue is best sorted out now, and can be done in a completely friendly manner easily - don't worry about it.
Here's what I would suggest to you and the band.
If you are an originals band, you could try to turn this situation around to your advantage. You could try mixing the styles that you differ over, and come up with something fresh and new - an original style and so forth. This is a great opportunity to create something unique so I would suggest that you try that first. What do you think?
Now mixing these 2 styles of music like this might gel and it might not , but it is definitely worth trying that first - who knows it could be the perfect solution for all as you race up the charts with your new sound <img src="/images/graemlins/smile.gif" alt="" />!
So ok let's say you give that a good go, have a few rehearsals and jam sessions - try an original tune using this approach and see what comes up. Give it a few weeks and get a great song together and if that works, write some more and build a killer original set with it and so forth - top of the charts right! <img src="/images/graemlins/smile.gif" alt="" />.
If you give that a try and it don't work out, well you can't say that you all didn't give it a fair go. If you are a covers band, well this idea wouldn't probably be a feasible idea. If you are a covers band, or it doesn't work out after this idea above, well it's onto the next step I think.
I think if you unsuccessfully tried to resolve the problem as above, or if you are a covers band, that you should agree to part ways in THIS band setup. This decision will benefit both of you and indeed everybody in the band, because musical differences like this will only slow down your musical progress. It's much faster if all of the band are on the same musical wavelength so to speak. There are many reasons for this which I won't go into here, but I wrote an article about exactly this type of thing before which goes into more detail about it. Hang on I'll have a look for the URL ... ah yes here it is on me guitar site:
<a href="UniGTR+ Article - record-company-deals-biz" target="_blank">http://www.universal-total-guitar-plus-center.com/record-company-deals-biz.html</a>
The sooner you realize that it would be better for all of you to move onto playing the type of music you WANT to, the better for all involved. If that involves a player leaving a band to find another more in his or her taste, so be it. So I would suggest that you make the decisions and follow thru with these "plans" as soon as possible. Hey don't worry about it, these issues come up all the time in bandland, and one day in the future you might have a good laugh about it as you sip your martinis. If you do get to number 1 in the charts let's know u never know <img src="/images/graemlins/smile.gif" alt="" />.
Good luck with it anyway, and don't forget that you can still remain good friends as you are AND sort this out. Let's know how you get on with it. <img src="/images/graemlins/irish.gif" alt="" />