Hello Andres!
"ace up your sleeve" means that you have a powerful and often secret weapon, advantage, etc., that can be used if it is needed. For example,
"The mayor's popularity among elderly voters gives him an ace up his sleeve for the coming election."
and
"ace in the hole" in this context is an advantage or a resource kept back until the proper opportunity presents itself. For example,
"His ace in the hole is his political influence."
So the meanings are similar but I think that you could say that "ace in the hole" has got a little bit more to do with timing.
I hope that helps!