compare a song to a room and each track to a ball in the room.....each ball is bouncing at different heights, the higher the bounce, the louder the sound.....
compression keeps a ball from having such a big of a bounce....say a ball bounces from the floor to 20 ft high....say your threshold is set to 10 ft bounces, a 10:1 ratio would make the bounce 11 ft......a 5:1 ration would make it 12 ft., a 2:1 ration would make it 15 ft....and it accomplishes this by bringing up the floor of the room....so with that 5:1 ratrio, the ball will be bouncing from where 8 ft was (now the floor), to the original 20 ft....so if you can picture that, the ball is still bouncing as high as it was(loud) but its a much smaller bounce.....
limiting would keep the floor where it is, but just specify that a bounce cant go past a certain space say 15ft.....sound a 20 ft bounce would go from 0 to 15ft then....
now if all your tracks are getting heavy compression, you go from a room full of pretty balls boucing in various heights, to this little small room with tracks not bouncing as much...all this loss of space(headroom)kinda makes the room dull.....
so compression is best left just to tame that sdtray ball or two of wild bouncing.....
whats the pros know ahead of time is to envision what you want the room to look like, and bounce the balls right in the first place, as opposed to taking a bunch of wildly bounced balls and trying to compress them into what you want.....