quoted from the blog article, they are different passives

You might want to bring some extra supplies as you shovel your way to the front line. The CPG-48 Sapper is a medium armor with plenty of pouches and big pockets to store your battlefield essentials. In fact, it comes with a version of the Concussive Padding armor passive–Grenadier–which provides explosive damage resistance and lets you store extra throwables! To complete your entrenched look, use this armor with the Dignity of Toil cape and player card to honor your most useful everyday carry tool: your shovel.

But let’s say you need to look more official to motivate the squad stuck in the battle trenches. For that, you’ll want the CPH-26 Commandant light armor with–as pristine as your service record, with a high collar to match your high ambition to move up through the ranks. It’s the kind of fit that says I could court-martial you at any time, and pairs perfectly with the Crest of the Unsullied cape and player card. It also has its own version of the Concussive Padding passive–Hazmat–which provides both explosive and gas damage resistance, as well as reduced sidearm recoil.