The goblins of Moria under the leadership of the chieftain will be more clearly distinguishable from the wild goblins from the lairs in the future. Moria goblins recruited in fortresses and camps will wear a black armor, which will give them an advantage when creeping around in the darkness of Khazad-dûm. As the chieftain's troops, these goblins are more disciplined and take care to keep their armor free from rust.
The wild goblins continue to wear the rusty armor and are available in the lairs on farm plots and the taken over creep lairs. In the latter, you will have access to pikemen in addition to swordsmen and archers.
The armies of the Misty Mountains are diverse, so it needed different banners to express that.
In the future, Goblin-town will carry the ram skull as its symbol, Gundabad the typical shape of the helmet ornament and the fortress towers, while Moria will keep the balrog head and the wild goblins the red grimace.
To show that Bolg unites the Misty Mountains under one banner, his banner bears elements of all four others.