Why do some teleplays have stage direction in all caps and some not?

Multicamera sitcoms (think: anything with a laugh track, like Seinfeld) and single-camera shows (sitcoms with no laugh track, like Malcolm in the Middle, as well as dramas) have slightly different teleplay formats. Multicamera scripts have stage direction IN ALL CAPS, with double spaced dialogue. Single-camera scripts look more like film scripts.

There are other subtle differences. For a detailed breakdown of the formatting elements unique to multicamera scripts, see our post on multicamera format.