If I can give you my experience based on a similar situation...
Met a woman I had a great connection with, lots of laughing, socialising etc... We wanted different things but decided that FWB would be a good thing to try, so for about 8 months, that's what we did.
FWB to me is about a "friend" that you also have sex with. That means socialising, meals out, movies etc... with the option of sex when it suits both parties. It's not a particularly committed relationship, and I personally don't see it as exclusive. IMO the only concern you have with each other's wider romantic life is that neither of you takes risks with the other's sexual health.
FB is a sexual arrangement. Booty call, whatever you call it. There is no socialising. It's that midnight call from the FB who's been out and is feeling horny and wants sex. Nothing more. Again, not exclusive, and purely physical. Again, making sure you respect each other's sexual health is paramount, and this is DEFFO a non exclusive relationship.
In my situation, FWB was great since we lived far apart, so only saw each other rarely at first. I continued to date and even slept with a couple of other women when things looked like they might be progressing.
What I didn't bank on was my feelings changing. Suddenly, FWB for me didn't seem enough so I suggested we became a couple. We did , and were actually incredibly happy for a while, but then something made her question what had been happening whilst we were just FWB. She thought I shouldn't have been seeing anyone else, whilst I assumed she'd been doing the same. End result, we split up, and I still feel devastated that I lost the best person I'd ever been in a relationship with, simply because we had different definitions of what FWB meant.
So, if all that was tl;dr.... The Short version is. FWB and FB will mean different things to everyone you speak to. If you go into one or the other, make damn sure you talk like adults understand boundaries and what the red lines are. Feelings WILL come into it unless you're incredibly detached. How you deal with those feelings will determine whether you find it a positive experience or not. Be REALLY sure in your own mind what you want.
Good luck.
RLD.