offstage

As a letter s

is the letter s with a.

As an adjective offstage is

of, or relating to that part of a stage not visible to the audience.

As an adverb offstage is

taking place offstage (as above).

As adjectives the difference between offstage and backstage

is that offstage is of, or relating to that part of a stage not visible to the audience while backstage is relating to, or situated in the area behind a stage.

As adverbs the difference between offstage and backstage

is that offstage is taking place offstage (as above while backstage is towards the area behind the stage.

As a noun backstage is

the area behind a stage, especially that of the dressing rooms.

As adjectives the difference between offhand and offstage

is that offhand is without planning or thinking ahead while offstage is of, or relating to that part of a stage not visible to the audience.

As adverbs the difference between offhand and offstage

is that offhand is right away, immediately, without thinking about it while offstage is taking place offstage (as above).