I own both.
The trigger and operation are the same on each. I prefer the grip on the A1 as it is a bit less slick. It seems to fit my hand better.
One difference between the two has been ejection, My A1 ejects all cases out at about 3:30. The M Ejects out at about 4:30. My M had a tendancy to send one case per magazine right back between the eyes, this stopped at about 500 rounds. The A1 never did this.