Magazine cutoff, speed feed, engraving and blue quality on the metal work along with better checkering on the stocks are differences between the two.
This pretty much sums it up except the Speed Feed did not appear until 1953, five years after M-11 production ended.
The M-11 was built under license for FN to circumvent U.S. import tariffs. It was a more utilitarian design so as to not compete with the FN model which was still imported though in limited numbers. The Remington did switch from an inside the trigger guard safety of one sort or another to a crossbolt safety before FN did which is/was a bonus. This feature was kept on the "American Browning" made by Remington from 1939-1946 or so and retained when production of the A-5 resumed at FN.
I've owned most of the variations of A-5s over the years along with a handful of M-11s, a couple Savages, and a Japanese knockoff imported by Garcia. All but two A-5s have hit the road and only one is likely to remain in the future. They are complicated compared to many of today's guns but they have proven to be reliable.
