Uniform velocity linear motion is defined as the linear motion with constant acceleration. The acceleration of uniform velocity linear motion is 0, and the acceleration is also constant, Is uniform linear motion equal to uniform variable speed linear motion?

No, because the speed of uniform motion is constant
In fact, you don't have to worry about this problem, you must treat uniform linear motion as uniform linear motion with a = 0

Can the direction of acceleration of linear motion with uniform velocity change
I know that the acceleration of uniform velocity linear motion is constant, but can the acceleration direction be changed
Do you have to move in the same direction with uniform speed change
But why is the sentence "acceleration of uniform velocity linear motion" correct?

The so-called variable speed linear motion includes acceleration linear motion and deceleration linear motion. The acceleration direction of the former is consistent with the motion direction, and its acceleration is represented by "+", while the acceleration direction of the latter is opposite to the motion direction, and its acceleration is represented by "-"
If it is a uniform linear motion, its value and direction can not be changed from the beginning to the end regardless of the acceleration direction. Otherwise, it is not a uniform linear motion and can only be called a variable velocity motion

Is the motion with uniform acceleration a uniform linear motion?
why

No. uniform velocity linear motion is a linear motion with uniform velocity, that is, constant acceleration

Is the change of displacement equal in the same time in the uniform velocity linear motion? Why

It is equal
If V1 is the initial velocity and V2 is the final velocity in T1, then V2 is the initial velocity in T2
T1 = T2 = t (equal time.)
Displacement change = v2t + 1 / 2at square - (v1t + 1 / 2at) = v2t-v1t
V2=V1+at
therefore
The change of displacement = t (v2-v1) = at square
No change at all
So the change of displacement is equal

Uniform velocity linear motion is defined as the linear motion with constant acceleration. The acceleration of uniform velocity linear motion is 0, and the acceleration is also constant, Is uniform linear motion equal to uniform variable speed linear motion?