It's kind of hard to read, but I found this comparison chart of features on the two machines:
http://www.countrykeepsakesquiltshop...0_Brochure.pdf
It shows that, aside from the difference in number of stitches, the 760 has 3 additional styles of 1-step buttonholes. I also read on Amazon that the hard case is option on the 720 but standard on the 760 (oops! that is also noted in the brochure comparison.)