Diffences between scene capture texture and viewport buffer?

i can see there is a difference between rtt (final color ldr gamma 2.2) and viewport buffer (scene texture postprocess input 0) :exploding_head:

to be sure : blend difference in postprocess material resulting differences mainly on edges

Is it due to a Antialiasing or resolution or ???

are they applied in the same way in RTT and VIEWPORT ?

help ! :white_flag:

anybody ? any idea on that editor viewport size ?