Well, there is 2 types of boxing commonly recognised (theres a third too, but thatll be explained)

Amateur and Professional.

Both have a distinct rules set different from one another. There is also white collar boxing which is more of an exhibition style format.

Amateur, headguards and vests (to stop your opponents gloves transferring sweat from your body to your eyes) has a white circle on each glove. The aim of the game is to score points by scoring successful hits on the opponent. The rounds last 2-3 minutes and theres usually 4 rounds maximum. Boxers usually wear larger gloves, like 16oz. Usually, knockdowns can be called if you hit a boxer hard enough to make him stumble or knock him back. Fights are called off much more readily and safety tends to be a higher priority. Most bouts are decided on points. Amateur boxing often requires boxers to start strong, throwing a lot of punches and lasting at that intensity throughout the bout, as it is comparatively short. Most professional boxers learn their trade by beginning in amateur before going pro.

Professional is different. No headguards, gloves are much smaller, no vest. 2-3 minute rounds, but up to 14 rounds. White collar is usually a similar format, but with fewer rounds and the rules can be changed to the boxers preferences. The stoppage rules are fewer, boxers need to be knocked down and unable to get up, or knocked down 3 times (sometimes theres no limit) to call the fight. If a boxer is unable to defend himself, it usually takes longer for the ref to call the fight in pro boxing. This is more about knockouts than amateur boxing and thus the referee allows it to happen. This type is more about the spectacle.

Very few boxers start in professional. Often they begin as an amateur boxer or a white collar boxer, in minor leagues doing exhibition matches, but its common for them to do both.

The headguard in amateur does provide some protection, but not as much as you would like to think. Youre still getting a massive jarring motion to your head and this is transferred to the brain mostly the same. Ive seen a few guys get knocked out wearing a headguard, I myself have been hit hard enough in one that I couldnt process information for a few seconds (sometimes temporarily couldnt see), so just threw my arms up and hopes to parry some incoming blows.

I'd invest in a custom fit mouthguard. The mouthguards you can buy for cheap from shops where you boil and bite them, arent worth it. Too many guys lose teeth in those guards and the insurance doesnt necessarily always pay out. Get a proper one made by a dental technician from an impression.

The structuring of boxing is complete chaos. There are athletics comissions or boards, who tend to put a skeleton rule set for safety in your country/county, then there are hundreds of different boxing organisations in which you can fight. You move up and down the rankings based on who you have fought and the outcome. The better boxer you beat, the more youll move up the rankings. This leads to many boxers wanting to fight washed up fighters. These being, boxers who have a good ranking from previous performances, but are getting old so arent as good as they once were. There are enough regional titles and belts for pretty much any decent boxer to begin winning awards within a few bouts.

Often events in amateur or white collar will consist of a days worth of boxing, many bouts, all one after the other. This is different to pro boxing where 3-4 bouts will be fought.