If you takeoff and land at the same airport and operate within 25nm of said airport, that falls within the definition of an "air tour" flight (not 135). If you provide instruction during the flight, then it could certainly be an instructional flight.

You might need a Part 91 LOA from the FSDO for conducting air tours. Recommend you contact your local FSDO.

If the purpose is transportation from A to B, now we're talking air carrier. Research the term "holding out" to the public....

Hope this helps