That's okay. I'm still new to FMA, and my background is mostly in Wing Chun. The two are pretty similar and complementary, by the way. But FMA is definitely a bit broader in scope.
Kali, Escrima, and Arnis are all generic terms for Filipino Martial Arts. There are actually tons and tons of Systems within Filipino Martial Arts. But most of them are somewhat similar as they've borrowed from each other. Specifically, I practice Lameco Eskrima, which is a synthesis of 3 major systems: Pekiti Tirsia, The Illustrissimo System, and the Caballero System. It also contains influence from a number of smaller systems. I also practice a bit of Pekiti Tirsia when I can make it down to train with one of our members here on MT
I'm sure others can give a better break down of the systems than I can, as I'm still fairly new, but FMA covers striking and trapping very similar to how Wing Chun does. The grappling is a bit more dynamic than judo or wrestling, consisting more of wrist-locks, disarms, and arm locks/breaks. It doesn't really get into prolonged, stand off wrestling in the same way as Judo, BJJ, or Greco Roman Wrestling because of the likelihood of weapons being involved. The grappling is there to compliment the usage of weapons, or any empty hand striking you may employ. If anything, it's fairly similar to a lot of what we do in Aikido, but more aggressive and offensive in nature. Like I said though, my knowledge of it is very limited.
My favorite aspect of FMA's is definitely the focus on weapons, though. The presence of a knife, a stick, or a machete really changes your outlook. The main reason I got into it was because I realized that, while I had a decent foundation in Wing Chun, I was not able to apply my empty hand skills effectively when a knife was involved -- simply because it's not something I ever trained to deal with. So, the knife defense aspect and use of improvised weapons is really why I've started training FMA's recently.