There isn't one. Trans and drag are entirely separate things. We may cross paths often as allies but it's not inherent.
As trans people, we may advocate for better care for trans children (typically in the form of social support and at most informed access to puberty delayers) but that has nothing to do with drag shows. We just exist, much like anyone else, living 24/7 as our preferred gender. You wouldn't notice if you passed us on the street:
Drag performers on the other hand are just that, performers. They entertain audiences much like a juggler or a magician might. Sometimes that's performing in adult-only shows (typically in bars), other times it's reading to children or lip syncing Lady Gaga. They wear over the top costumes and act dramatically but at the end of the day it's just a costume. You'd know if you passed a drag performer on the street:
I don't blame you for any confusion since conservatives have been trying to muddle the waters ever since they learned the word drag, in part as a scare tactic to demonize trans people and make us scarier than we are. But there's no reason to fear either.