Necronomicon, the one true Book of the Dead spoken of only in hushed tones in fear of its powers in all of H.P. Lovecraft's books. Literal translation is something like "Guide to the Dead."
Necrophilicon, that thing in the basement of the cathedral in QFG4 written about by P.H. Craftlove. Literal translation is "Guide to Sex with the Dead."
Nyah.
Please excuse me for being off-topic, but I need to say that:
First of all, there is no evidence that Necronomicon is an actual occult text. It is a fictional book written by HP Lovercraft. It actually translates as "Of the Law of the Dead"
And Necrophillicon translates as "Of the Love of the Dead"