That was probably our Ebay person who posted that seeing as we are one of the only people selling the LK-7500. It is the same hardware, lens and thus video quality. The difference is that the operating temperature is lower (but still very functional) and the mount is different. The price is also lower.
I can't speak to the internals (although I am interested to see just how identical the hardware is) but I can say that I like the cosmetics of the LK-7900's exterior over the square casing of the LK-7500. If price is an issue and this information is accurate I would totally recommend getting the 7500. I love my 7900 and it's by far the best dash cam I have owned.