5S's M7 vs. N5's tracking sensor

I wanted to pose this question to the great people of The Verge: What are the differences and similarities of the M7 in the 5S and the tracker that's in the N5?

Apple gives things names and tech bloggers write a million articles about it (just google M7 and see what you find), but I don't think I've seen one review/hands-on that mentions and goes into detail about the tracker that's in the N5 and what it does and can enable in future apps. I'm currently reading Anandtech's M7 article.