what is precheck? It’s been a few years since I’ve flown, but we always do the early check in with Southwest, is that the same thing? Or is this something new?
Pre-check is TSA screening that you do a background check and get finger printed and pay around $80 for 5 years (but any minors 12 and under go through with you and don't need to be Pre-checked.) If you pass you get a KTA (known traveler number) You use that number when you book your flight and can use the expedited screening lanes at the TSA provided it is notated on your boarding pass.
So, not the same thing as Early Bird on SW.