Why similar corvettes and frigates differ in size

Why do modern light frigates and corvettes with similar paper capabilities have dramatically different displacements?

Their size is often driven by operating range, sea conditions, endurance, and support assumptions rather than the weapon list alone.

The weapons fit visible on paper does not necessarily drive displacement. Designers must also provide for the oceans and weather in which the ship operates, distance from home, crew endurance, maintenance, stores, and the shore infrastructure available to support it. Hull volume buys seakeeping, range, repair margin, and the ability to remain deployed without frequent external help. Two ships with comparable headline systems can therefore be very different sizes because they are built for different operational lives.