Aren't you comparing mobile CPUs to desktop?
The 6200U is a hyperthreaded dual core, while the i5 2400 has four cores.
Some other factors are the 6200U operates at a 25W TDP for mobile applications and has a lower clock speed (2.8 GHz turbo). The 2400 turbos up to 3.4 GHz and doesn't have the same TDP restrictions, being a desktop part, and has additional cache.