What is the difference between the outodoor airplane and the indoor one?

indoor airplanes are electric and pretty small.....where as outdoor aircraft can be very large 1/2 scale weigh in at 100 lbs or be as small as indoor aircraft......out door aircraft can be powered with electric, glow, or gasoline...

Size and speed basically, which greatly affects how much space you need to fly them.</p>

you can have some fun with indoor helis, but not with indoor planes.. i think it will be very hard to maneuver.

They make some highly maneuverable indoor airplanes. They are just tiny to work in the smaller spaces. They are also built lighter too because without wind indoor flight stresses are lower.