How substantively different are they? Am I obligated by them?
Have you been raised in a basement?
No.
Do you ever read books?
Yes.
Someone using their reason is being moral; someone who denies it is being immoral.
Hmmmm. I'm going to let that one percolate for a while.
Cordially,
"How substantively different are they? "
Quite.
"Am I obligated by them?"
Only if they are right. Do they recognize reason as the foundation of morality or is it feelings and supernatural commands?