IDK if this search result is going to work via link:
elitebook 2760p vs 8440p - Google Search
A quick and dirty is that the 8440 is physically larger than the 2760, might have an Nvidia GPU, and is otherwise a whole lot the same machine aside from the convertible aspect of the 2760.
If the product doesn't meet your needs or is different from the advertised item (and is an issue for you) take up the buyer protection and return it.