Let's start with the front and the profile. These areas are technically the most similar, since both cars feature high beltlines and have lower fascias defined by large inlets and a deep chin spoiler. And admittedly, the little kick-ups on the lower rear portion of the side windows are reminiscent of each other. But that's where the similarities end.
Up front, the grille is by far the clearest indicator that the Honda is most certainly a Honda. The wide "blade" shape that spans the nose from light-to-light is unmistakably from the company that gave us VTEC. After all, just about every Honda today uses some form of that grille. The Subaru, on the other hand, has a traditional grille that is distinctly separated from the lights. It's not a bad thing, Subarus have had rather anonymous designs in the past, and we've still liked them. It's a Subaru thing. Moving to the scoops, we find more differences. For once, the Type R is more restrained, with a small, low-profile inlet far back on the hood. It will not be mistaken for the massive one on the STI, which looks like it could suck up low-flying fowl.
Along the side, the distinctions continue to pile up. The key here is in the fenders. While the STI has proud, pumped-up fenders compared with its distant Impreza cousin, they aren't nearly as pronounced as those on the Type R. The Honda's flares clearly show that they protrude from the standard hatchback's sheetmetal and closely follow the curve of the wheelarches. The STI's fenders proceed along the body's lines more closely and blend in more.
Finally, we come to the rear, where no one should ever get these two vehicles confused. Yes, they both have enormous rear wings and diffusers, but that's it. For starters, one car is a hatchback, and the other is a traditional sedan. Not only that, but the Type R's hatch has a distinctive split rear window. I mean, based on the criteria people have used to compare the Type R with the STI, they should've actually been comparing the Honda to a Prius. The Type R has much more radical aerodynamics as well, with extra protrusions off each side of the wing, and two little fins leading from the roof toward it. The taillights of the Honda and the Subaru are very different, too. The "boomerang-style" lights of the Civic look nothing like Subaru's simple units. The rear bumper of the Type R also features far more detail, arguably too much, with the diffuser and the rear air vents. Plus the Type R has that distinctive, Ferrari-esque, triple exhaust tip.
So there you have it, a very long-winded explanation of how two cars don't look alike. And really, it doesn't matter all that much. Not because this is all opinion and many people will have a different one than mine, but because no matter how similar they do or don't look, you'll hear the difference before you see the cars. Nothing sounds like Subaru's boxer fours. So no one should have any trouble identifying the two anyway.