They have a chain of command but not a ranking system like PD or Fire.
You have the VSTs and EMTs who are pretty much the bottom of the barrel. You then have AEMTs (if your area uses them). Followed by Paramedics. Then you have field supervisors or associate supervisors. Then you have paramedic supervisors/operation supervisors. Then you have your operations manager who is in charge of day to day needs of the operation. Then you have a General manager who oversees multiple divisions. Those are really going to be the main people you interact with.