H4 is 4 tracks for overdubs ONLY... (and VERY limited ability - no punch in/out, top to bottom one take only). H2 can record in 4 track surround, but not overdub.

H2 is a computer interface also (exactly the same specs), and instead of the one X-Y configuration, you get TWO different sets of mikes, one at 90º and one at 120º (plus you can run both at the same time for either two track stereo front and back - good for putting it in the middle of a bunch of guys jamming, or in four track surround, good for effects work, field recording, interviews, etc.)

But yes, the H4 has XLR inputs, but the gain is a little noisy, IMO. I used an H4 prior to the H2. I believe the H2 is the better deal, and put my money into it...

If you are looking for a REAL four tracker, you need to look elsewhere than the H4, IMO