Probably" carries a greater degree of certainty, it means reasonably true without much doubt. Ex- Probably it will rain. ( 90% chance) Maybe" means possibly but not certainly. Ex- Maybe it will rain. Maybe it won't. (50% chance) ........................................................................................ Probably means the likely hood it will happen is high, maybe means there is no way to know if and/or when it might happen if it happens at all.

*probably= almost certainly *maybe = possibly