They look the same (except for the space) and they sound the same. They also have a similar meaning, so what's the difference and how do you use them? Basically, maybe means 'possibly' or 'perhaps', and may be means the same as 'might be'. In terms of grammar, maybe is an adverb and may be is a verb phrase.
Examples:
He may be the fastest runner in the world.
I may be a little late.
The train is late. Maybe it's because of the weather.
'Can you go to the party?' 'Maybe. I'll have to make sure.'
You can swap may be for 'might be' and maybe for 'possibly' or 'perhaps' in the sentences above without changing the meaning.
Practice:
Insert maybe or may be into each of the following sentences (click 'continue reading' for the answers):
I the only person who can do this!
I able to help you.
nobody will notice that your hair is blue.
That the best thing to do.
that's not such a good idea.
NOTE: Be careful with other sentences that use 'may' and mean that something is/is not allowed, for example:
You may sit wherever you like. = You can sit wherever you like. (You are allowed to sit anywhere.)
This information may be used in classrooms. = You are permitted to use this information in classrooms.