Amphitheatre vs. Theatre

Difference Between Amphitheatre and Theatre
Amphitheatrenoun
An open, outdoor theatre (which may be a theatre in the round, or have a stage with seating on only one side), especially one from the classical period of ancient Greece or Rome, or a modern venue of similar design.
Ancient Roman amphitheatres were mostly oval or circular in plan, with seating tiers that surrounded the central performance area, like a modern open-air stadium.Theatrenoun
alternative spelling of theater
Amphitheatrenoun
(geology) A natural formation of a similar shape, where a steep mountain or slope a particular rock formation forms a partial or compete bowl, especially one used as a performance space (and possibly modified by carving out seats, etc) because the slopes naturally amplify or echo sound.
Theatrenoun
a building where theatrical performances or motion-picture shows can be presented;
the house was fullAmphitheatrenoun
a sloping gallery with seats for spectators (as in an operating room or theater)
Theatrenoun
the art of writing and producing plays
Amphitheatrenoun
an oval large stadium with tiers of seats; an arena in which contests and spectacles are held
Theatrenoun
a region in which active military operations are in progress;
the army was in the field awaiting actionhe served in the Vietnam theater for three years