In the past, when I've heard the 'less additive form', it was in contrast to nicotine from tobacco, where there are other chemicals and compounds at play. While it's true ROA can be a big part of habit formation, I'd argue it's a stretch to call it different form when it's the same chemical in either case.

tbf tho, I am somewhat contradicting another comment I made about bioavailability on this very gp thread so suffice to say, I do understand your point.