depending on the frame width, you could actually "physically" fit another frame in the box. When you can, that is nice for storage. But like a can of worms, once you open it, the only way to get all the worms back in the can is to get a bigger can.

There are a couple things to be aware of, though they will not affect you in the immediate future. First there are people that feel frames should be thinner than they normally are, which would (if you made frame modifications) actually allow you to fit an extra frame in the box, thus keeping the bees closer together and encouraging certain things that in that discussion are desirable. This is a specialized and somewhat advanced thing, that is interesting and worth reading about, but I think would not be generally useful to most people, and make manipulating things a bit harder.
Secondly, you may find that there are times when you may only want 9 frames in there. Depending on whether you are using all 1 size (same size box for brood nest and supers) there are people that when all the comb in a super is drawn out and being filled, they will pull out a frame going to 7 in an 8 frame box or 9 in a 10 frame box. Then they use a tool that will evenly space all the frames. If you ever buy a "getting started toolkit" or one of those type of packages, you may get one in it, and not know what it is or what to do with it. It is a straight line with a bunch of triangles. Looks something like this:
The reason being that they will build deeper comb for storage (up to a point). This is kind of a good thing in honey supers, and the opposite is desirable in the brood nest.
Anyway, probably more than you or anyone ever cared to know about frames and spacing and boxes. But looks good, 10 frames will not be nearly as loose when you have a bunch of bees in there and they start building comb and propolizing things. You will appreciate the extra space.
