The blue one is the edge stile, that is, the border of the door and window, where it connects with the wall. Red is the middle stile, which is not connected with the wall and is mainly used for supporting and glass division. In fact, there is a part called fan profile, which is the material used to open the fan part.
Another way of saying it is:
(1) Panel doors in general doors and windows are composed of door frames and door leaves, which are divided into door core plates, upper middle vertical plates, lower vertical plates and two frames.
These two boundaries are called side stiles.
(2) In my opinion, a door consists of a door frame and a door leaf; The door frame comprises an upper sill, a middle sill and left and right frames; Door leaves include upper vertical plate, middle vertical plate, lower vertical plate and left and right vertical frames, which can be described as "heaven". The upper vertical plate is three horizontal, and the left and right vertical plates are two vertical.