You can get Glock parts from a lot of different places (like
www.glockmeister.com). Both Glock and Springfield have good service departments, though.
They both seem to have similar if not the same safety features, easy to clean, and are accurate from what I'm told. They have the same look and feel although I never shot any of them before.
Safety features: the XD features a grip safety, and the Glock does not. I personally do not like the grip safety, but you might prefer it. Mostly it's a matter of taste. The one difficulty I have seen with a grip safety, and the reason I don't like it, is that for some people it can be hard to hold the grip safety down while retracting the slide. If you have to shift your hand around in order to pull the slide back, it could be a problem for you. If not, it won't be. All depends on hand size.
Both are easy to disassemble & reassemble, both are easy to clean. Glock might have a
very slight edge there, but if so, it's very minor.
Looks are very similar, though to my eye the XD is slightly more attractive.
Feel is slightly different in a couple of ways.
The triggers are very alike because they both have the trigger safety nubbly thing, but the trigger on the XD is going to be a little crisper when pulled and it is thus slightly better.
The grip sizes are very similar, but the grip angles are noticeably different. Most people seem to prefer the grip angle of the XD, but plenty prefer the Glock. You'll have to figure out which one works with
your hands. My hands are the same size as my husband's, but he prefers the XD and I prefer the Glock -- probably because my wrists are more flexible than his. Handling them in the store would be good, and it would be better still if you could shoot both. Couple of folks I know prefer the
feel of one but actually shoot the other one better.
That's about it. Oh, if I remember right, the XD is a little heavier. Not enough to matter, just something else to look at. Heavier generally means a little less felt recoil when you're shooting, but it also means less pleasant to carry around.
Can I ask why as a new shooter, you've chosen to go with the .40 instead of a 9mm?
pax