Ugh, I've heard a couple different things (I hate trying to sort out tinc morphs!). I've heard they are the same, someone bred phallids and marketed them as oyapoks (or the other way around), that there are two lines of oyapok and one got labled phallid, that one or the other "true" example of that morph isn't actually in the hobby, at least in the US.
In truth, I have no clue.
In truth, I have no clue.