That red one is not an Si. The sunroof in it is glass, not metal like the OEM one. The blue one has Si wheels, but Si's never came in that color, not to mention that the blue one is a 90 or 91 by the picture but those are 88-89 Si wheels. My guess is that they are both DX's.

Like jaje said the best way to find out what model they are is to look under the hood. The DX came with dual point fuel injection which will look like a big Circlular piece on top of the intake manifold where the Si and HF come with the traditional log style Multi port fuel injection manifold. The HF throttle body will look so small that you can almost clog it with a quarter (and inch and a half in diameter, MAYBE) where the Si throttle body will look about 2 1/2 to 2 3/4 in diameter. The valve cover on both the Si and DX with also say 16 valve.