It's the difference between a 1920s produce truck and a modern diesel delivery truck. Bigger, more capable, many incremental improvements in all systems, optimized for wartime, but no major obvious changes.

Some of those incremental improvements would be things like double-planking, copper bottoms (arguably not incremental), larger gun decks, bigger guns, framing to reduce hogging, better powder handling, etc. But a ship of the line was recognizably just a later member of the galleon type.