They are synonimes, at least in this context (referred to time). Examples with praetereo (praeter + eo, eo = go, so it means to go further, beyond, to pass by):
nec praetiritum tempus revertitur (past time never comes back)
iam praeteriit aestas The summer is already gone.

With transeo
Dies transeunt: the days pass
imperium brevi transiturum: empire that will soon pass, that will not last much.

I see "transeo" is used in present and in future more than "pratereo", so it is more suitable for the idea you want to translate. Indeed, "praetereo" gave "preterit" in English, and similiar forms in other languages, which means "past", so is more suitable to express an idea on past things.