Total supply counts everything issued so far regardless of whether it can trade. It sits between circulating-supply and max-supply, and it rises with every mint and falls with every token-burn.
The gap between total and circulating is the pipeline of future sellers: team allocations, investor tranches, treasury reserves and unclaimed rewards.
Example: 1bn total with 200m circulating means 800m tokens waiting. Whether that matters depends on the token-unlock schedule; 800m released over ten years is very different from the same amount over twelve months, even though the supply figure is identical.
Related: circulating-supply, max-supply, token-burn, token-unlock