The Eloi and the Morlocks are definitely foils – for anything you can say about one, the opposite is almost always true of the other. One of them is afraid of dark, the other is afraid of light. One of them is beautiful, the other is hideous. Straight down the line, the Eloi and the Morlocks are opposites. (For more examples, check out "Characters.") One exception: both of their hands are described as soft (4.2, 6.7).
According to the Time Traveller, both the Eloi and the Morlocks are the descendents of 19th-century humans. So the Morlocks are descendents of people like "the East-end worker" (5.38), who is notably absent from the Time Traveller's dinner parties. In fact, most of the 19th-century people in the novel seem to be upper-class professionals, and we see them relaxing leisurely, so the dinner guests seem a lot more like Eloi than Morlocks.
The one exception might be the Time Traveller himself, who is active and a meat-eater, just like the Morlocks. Like them, too, he's also mechanically inclined. What's even creepier is that he sometimes uses words related to eating when he's talking about other people, which kind of makes him sound like a cannibal: he calls the Eloi "delicious people" (4.32) and when he hits the Morlocks, he describes the sensation as "succulent" (9.10). Yeesh.