Hello @Tim J ,
my initial guess was that the final letter can indicate the license level
A = Network Advanced
E = Network Essential with A better ( more features ) then E.
Looking at Cisco Commerce Workplace CCW
ISR 1100 4P DSL Annex A w/ LTE Adv SMS/GPS 802.11ac -E WiFi
ISR 1100 4 Ports DSL Annex A and GE WAN Ethernet Router w/ LTE Adv SMS/GPS EMEA 802.11ac -E WiFi, POE+, SFP+, Software Licenses, and Performance Options
the A version says:
SR 1100 4P DSL Annex A w/ LTE Adv SMS/GPS 802.11ac -A WiFi
ISR 1100 4 Ports DSL Annex A and GE WAN Ethernet Router w/ LTE Adv SMS/GPS NA 802.11ac -A WiFi, POE+, SFP+, Software Licenses, and Performance Options
Actually final letters refer to WIFI standard version supported.
Hope to help
Giuseppe
