Full tilt uses the same shell for their high 5, and booter, definitely a boot made to fit a higher volume foot. Where the major differences lie is in the flex, and the buckles. The freesoul 10 comes with a 10/10 tongue and higher density intuition liner, the freebird 8 comes with a 8/10 tongue and slightly lower density intuition liner, and the 6 comes with a 6/10 tongue and standard foam liner. Feel free to message me with questions, I can definitely help there. and check out the new boots for next year!
http://www.roxa.com/?lang=2