TSOP and TSSOP are not exactly the same.
TSOP is a thin surface mount package with a small volume and pin spacing, and is often used in small electronic components.
TSSOP is a thin and reduced SOP package with smaller size and pin spacing. It is often used in ultra-small and high-density electronic components.
Therefore, although TSOP and TSSOP are both surface mount package forms, they differ in size and pin spacing.