In LOR origin determine what sort of spells you can learn. Your spellls for your spell list can be selected from any origin
There are only 4 Origins in LOR. Spellcaster classes often grant access to one origin. When you are granted an origin, you can select any spell from that origin provided it does not have a sub-origin that has the word (Restricted)
Sub-origin refers to unique spells. If you gain a sub-origin, you unlock all spells with the sub-origin tag no matter its origin.