The silhouettes are the same.
Actually, the silhouettes are different and historically accurate. Have a closer look...
(I'd have posted this sooner but Photobucket wasn't working for me.)
The first counter shows a mounted Bren gun as this is the usual configuration for the Carrier Platoons as well as the Scout Carriers.
The second shows the ammo trailer of the mortar carrier. The 4.2" mortar itself could not be fired from carrier. It is disassembled and in the carrier, out of view.
The third shows a mounted Vickers MMG. This gun could be--and frequently was--fired from the carrier but the increased vibration made it less accurate (which in game terms equates to a shorter range when mounted).
The fourth shows a mounted 3" mortar. While this mortar could be fired from the carrier, this wasn't normally done (and isn't allowed in the game) because it tended to wreck the transmission.