Currently, you can regain HP/MP while moving in passive mode regardless of whether or not you're incurring enmity (or aggro), whereas after 1.19 you can only regain HP/MP if you remain in one spot in passive mode while incurring enmity (or aggro).

Now, whether you can regain HP/MP while in passive mode while you're moving is something that I'm not sure of (or at least, wasn't 100% convinced from the patch notes).