I’ve never written a play, nor felt the urge.
I suppose there are quite a few differences. In a stage play:
– you’ve got no choice of camera angles, close-ups etc.
– you can’t cut rapidly and easily between locations
– fewer special effects
– limited cast – probably no extras
– action sequences are risky
– etc etc
But those are just practical issues. There’s also expectation. I think a play is often expected to have more weight (even if it’s a comedy). Dialogue is not expected to be so realistic – your characters are even allowed to go off on a monologue or two, if you feel like it. Especially if it’s a comedy, you have to bear in mind the interaction with the audience.
Cinema is about “cinematic” experiences. “Show, don’t tell.” TV less so, though I would argue that that is changing. TV goes for verisimilitude. Theatre is still more accepting of conventions and “theatrical” staging.
The interesting comparison is with traditional, studio-based, TV sit com, which has its roots in theatre, and still follows many of the conventions.
Just a few random thoughts for you!