These two words are used for saying that you are not certain about something, or that something may or may not be true.
Perhaps is more formal and is used in writing while maybe is used more in spoken English
I wondered if perhaps he had changed his mind about attending the party.
- When can you give me an answer?
- I don't know. Maybe tomorrow.
These two words can confuse even native speakers.
Probably is used for saying that something is likely to be true, and possibly that it may be true but you are not certain.
If house prices are low, it's probably because there is a lack of demand.
- Would you consider moving to another country for your work?
- Possibly, I'm not sure.