Why modern destroyers blur into cruisers

Where is the dividing line between a destroyer and a cruiser today?

The line is blurred: frigates and destroyers emphasize different escort missions, but many large modern destroyers are cruisers in practical capability.

A cruiser is defined here as a general-purpose combatant, which makes Zumwalt and Arleigh Burke-class ships difficult to contain within the destroyer label. Frigates tend toward anti-submarine warfare and destroyers toward air warfare. Both still need credible capability in the other domain, so mission emphasis matters more than a rigid boundary. The modern fleet can therefore be understood as light and heavy cruisers differentiated by emphasis, radar size, and associated power demands.