Demisexual means you are only turned on sexually by someone to whom you have a deep emotional attachment.
Pansexual means you can be turned on by (nearly) anyone.
As far as I know, sapiophile and sapiosexual are almost synonymous, except perhaps that sapiosexual leans more toward physical attraction to someone of high intelligence, whereas sapiophile may include broader feelings of attraction, not necessarily only sexual ones.
According to these tests,
I am barely demisexual (I scored 61 points, 60 qualifies).
I am not pansexual (I scored 39 points, 60 qualifies).
I fall short of sapiosexual (I scored 71 points, 75 qualifies)