What's the difference between small forward, power forward and shooting guard in basketball match? Detail point

Let me sum it up in my own words.

Power forward: Usually there are more blue-collar workers, who assist the center in rebounding, covering, blocking and defending. A good power forward should also have the ability to throw near the restricted area.

Small forward: usually an important scoring position for the team. Small forward should basically have three-point basket, speed and breakthrough ability, which is the key part of the team's attack.

Shooting guard: Since it is called a shooting guard, it is a guard, but unlike a point guard, the point guard focuses on scoring, and the point guard focuses on organizing the team and realizing the coach's ideas. Usually, shooting guard and small forward are the two most important scoring points of a team, but now there seem to be more stars in the shooting guard position in nba.