It’s mainly surface area and chemical additives. Making the separator thinner increases capacity, but increases internal resistance and chemical stability is sacrificed.
Using hexagonal grids in the cell allows for lower IR, and lower capacity due to a decrease in active material mass.
In high drain applications, medium capacity high drain cells are preferable to high capacity medium drain cells like 30Qs and HG G2s, because of lower internal resistance, more capacity is kept intact, and less heat is produced, leading to higher cycle life. However, this issue is usually mitigated in parallel packs due to spreading the load across ≥2P.
In single cell high drain lights with higher than 15A draw, I would recommend something like a 24S, due to low heat generation and higher cycle life. At ≤15A, a 30Q/HG2 is great.