A referee is involved for the purpose of enforcing pre-determined rules that were mutually agreed upon by each opponent.
There are often timed rounds with a short break in-between where a player can catch his/her breath, get a drink of water, get some advise from a trainer.
The match is in a well lit, dry, level, soft venue.
The opponent is unarmed.
The opponent is alone with little chance others will join in.
Some sort of safety gear is usually involved i.e. cup, mouth piece, gloves etc.
The opponent usually isn't trying to kill, maim or severely injure you.
If you've had enough, you can call a time out or tap out or simply quit and walk away.
The prize is a ribbon, plastic trophy or maybe cash. (depending on the competition)
Such training could utilize refined motor skills. It could employ a particular strategy i.e. wear the opponent down, put them against a corner and tie them up with a submission etc. Such strategy may involve making the match go long on time.
As a comparison, self-defense training is for situations;
Where there is no referee enforcing rules. You are likely alone and/or at some sort of a place or position of disadvantage.
There are no rules.
There are no breaks, water, advice or anything to assist you.
The assault can occur in a parking lot, elevator, side street, your car, your bedroom, in the woods etc. I will likely occur in dim light conditions in any type of weather.
The attacker may be armed, and should be assumed to be armed.
The attacker may have friends more than willing to jump in.
There is no safety gear, but likely a plethora of person-unfriendly objects like broken glass, traffic, walls etc.
The attacker is looking to cause as much damage to you as humanly possible in the shortest amount of time possible.
To quit is to die (or something possibly worse i.e. rape, love one killed etc)
The goal is survival, the method is whatever it takes.