The guitar bridge is where the sound vibrations come from, and it supports the transmission of these vibrations to the chamber. It is the means by which strings vibrate freely and efficiently to a larger surface. Scrutinize the bridge closely and see what conveniences (and limitations) it presents on your logistical and technical concerns, such as string buzz, compatibility with pickups, etc. Action, meanwhile, is the space between the strings of the guitar and its neck. If you are only beginning to learn how to play the instrument, then be sure to choose a guitar that has relatively low action. That way, your fingers won't be distracted by the effort of having to reach for the strings.