i think it's just a standard sergeant. White helmet is veteran, and the laurels on it can also denote rank (i think while helmet with red laurels is vet sergeant)
You are mostly right.
According to the Codex Astartes normal sergeants have red helmets (or wear the symbol of a red skull), vets have white helmets, sometimes addtionally with laurels in chapter color and vet sergeants have red helmets with a white stripe or white laurels or both.
red helmet? is that like a Vet Sergeant or something?
i think it's just a standard sergeant. White helmet is veteran, and the laurels on it can also denote rank (i think while helmet with red laurels is vet sergeant)
You are mostly right.
According to the Codex Astartes normal sergeants have red helmets (or wear the symbol of a red skull), vets have white helmets, sometimes addtionally with laurels in chapter color and vet sergeants have red helmets with a white stripe or white laurels or both.