The top one is a Brenn LMG.
In the 70s I was trained on both the Brenn and the GPMG (Jimpy). From memory I preferred the Brenn mainly because it meant less faffing about with and was more soldier friendly ..
The IRA also used a couple of Brenns with the old wooden stocks that had receptacles meant for oil cannisters which coincidentally could be made into the size of a location beacon, movement detector and small batteries .....