Ebola belongs to a virus family called Filoviridae, aka filoviruses, which also includes the Marburg virus (see sidebar).
But unless you live in central or west Africa (or travel there), you aren't that likely to come across the filoviruses. That's where four of these Ebola species originated. There are the Zaire and Sudan strains, which are the most deadly for humans, as well as the Bundibugyo and Tai Forest varieties, which have only been seen a few times. The fifth type, Reston, is the only non-African variety, having originated in the Philippines, and it's the only one that doesn't cause severe disease in humans [source: CDC].
Like all families, the filovirus family members look like each other. The worm-like shape of a filovirus is often described as "hooked," like a shepherd's crook. They all get their genetic material from RNA, instead of DNA the way we do. And their genetic information is not terribly complicated. While humans have 3 billion base pairs in their DNA, the molecules that make up the RNA of a filovirus only number about 19,000 [source: VanMeter and Hubert, ViPR].
Of course, the biggest likeness among the filoviruses is that they all kill their victims very similarly.