In my mind, without +/- is a way of seeing what kind of student you are. If your institution doesn't award +/- grades, well then there's no difference. I am assuming, however, that the majority of schools do award +/- grades.
So here's my take on it, but I'm not on an adcom!
If your +/- average is BETTER than your non +/- average, this says that you got more + grades than - grades. This can be good, as getting more B+ grades is better than getting more B- grades.
If your +/- average is WORSE than your non +/- average, then this says that you got more - grades than + grades. This indicates that you could have performed better by maybe making a B instead of a B-, or an A instead of an A-. I use my case as an example. An image of my verified GPAs are attached. I got more B- grades than B+, and so the non +/- seems to say "if he had only worked a little harder...he might have had a GPA like this..." haha.
However, if both GPAs are still good and don't differ much from each other, which I feel like mine probably are, I don't think it matters much. A lot of this is probably just over analyzation as well. Just do the best you can, submit your app, sit back, and wait for good news. 👍