VOL is the short BASIC-style way to change overall generated-sound loudness. It affects the master level used by sfxlib output rather than one individual channel.

Use VOL when a program only needs to set the volume and does not need to read it back. It is good for simple examples, quick sound tests, and programs written in a compact older BASIC style.

For new code that needs more control, VOLUME is usually clearer because it can set the master level, set a channel level, and return the current level.