Well, I'll start answering my own question, if anyone else is interested!!
Maybe someone has some further input too...
I just found a website that indicates that fever blisters and cold sores are the SAME THING, just different name. And that canker sores are different. Essentially, boils down to, if you get a herpes outbreak inside the mouth, it's mainly on the roof of the mouth or the gums, and the sores are generally smaller than canker sores.
Canker sores are more likely to occur on the inside of the lips and cheeks, and the tongue. Usually quite small, but can be up to an inch.
Canker sores are not caused by a virus or bacteria, but MAY be due to deficiency in diet or allergies.
If anyone's interested... I think I have canker sores, not oral herpes (genital is enough, thank you very much!!). My diet sucks anyway, maybe I'll try to eat better!!
(But Christmas is coming!!)