What is the difference?

good question. Same vdimm, timings and speed.....

I7 compatibility. Heat spreaders. I would have to guess the expensive ones might OC better.

Might be worth saving money though?

Uhm, looks like the difference is the model number... and the heat spreaders. They might be higher-binned chips, but it's hard to tell.

Yeah, I'm gonna go with looks and those heat-spreaders. I would save your money for a month or 2 though. The price on DDR3 is going down real fast.

That is weird. Usually the ones with the fancy spreaders are the high performance G.Skills, but in this case it apparently isn't.

One is priced over $200 the other isnt. Of course.

The more expensive memory is their HK series, which they consider their premium memory. I would guess it has the best memory chips on it.
Their old HK 2x1 DDR2 800 sticks (the black ones) were some of the best overclocking RAM out.
Not sure if it is worht the $129 difference though.

So, you think I can use the cheaper one on an i7 board?