It's that מול does not translate to "in front of". It's opposite, across or facing
and לפני is before or in front
The preposition "מול" means opposite to or in front of, "לפניי" means before me.
Say I am standing, and there is someone standing and facing me and I am facing him. Could I use either preposition?
Technically yes. To be more specific, "מול" refers to a situation in which you are facing something/someone (but that something is not necessarily facing you).
While "לפני" just means that something/someone is before you, like in a queue or a race. It can also mean face to face, like in your case.
if מול means facing something/someone that is not necessarily facing you, does לפני mean the same ?
So לפניי can mean "in front of" & "before" (in position),
but can it also mean "before" as in time ? ( like : He (always) stands (up) before me ? )