WW2 Rank appointments

[Bill Miller]

The past week or so I have been tabulating some nominal roll information and it has made me curious as to what exactly were the subtle differences between:

Acting Lance Corporal > L/Cpl > A/Cpl
Acting Lance Sergeant > L/Sgt > A/Sgt

Forgive me, but from my civilian background, these "intermediate" appointments seem kinda pointless. A title (and presumably responsibility) without a pay increase? I see many of these same men were also granted reversions "at their own request".

Thanks,
Bill.