If I select one face without any tools (like… the tool which appear if I press B, or the tool which appear if I press B 2 times…) so just with the right mouse button, I’m getting a selected face with tiny white pixels in it like this one:
But if I use a tool I don’t get those white pixels… what’s that? Is that the active face now? I watched tutorial videos and those white pixel faces never appeared in those videos
Basically, yes. Just like you have an active object when in Object mode, Blender also maintains an active face, edge, or vertex in Edit mode, depending on your selection mode.