I only own one phrag so my on hands experience is very limited. I tend to stay away from them cause they either tend to like it cooler than strap leaf paphs or get way to big for me when their blooming size.
But from what I know and comparing my lone phrag sunset glow to my paphs. phrags dont have molted leaves just strap leaves. paphs come either molted or strap leaf. Also new root tips on phrag looks more hairy than new roots tips on paphs. My phrag leaves dont look as glossy as my strap leaf paphs.
I'm sure other's who've had more first hand experience on this will chime in.