The TISA (reg DD) rules are more strict. You have to spell out A_P_Y_; must express it to the .01% and, if you say any other rate, it must be the "interest rate." The TILA (reg Z) rules are more relaxed. You can say APR or Annual Percentage Rate; there's nothing about how far (or how little) you express it to; and you can say "rate" or "interest rate."
With all of that said, if you are going to list mortgage loan rates on your website, you're likely going to state the term for various rates. If you do, you trigger lots more info. Be sure to read 1026.24(d) about what is triggered and when and 1026.24(b) about the "clear and conspicuous" disclosure requirements. Most institutions do not list specifics about rates because the clear and conspicuous requirements demand so many things and require this info to be right beside the disclosed rate (not mouse print at the bottom). It becomes very hard to make things clear and look nice at the same time.
Good luck!