Why does neutral white LEDs have lower output than cool whites?

[strinq]

It is always the case that a cool white emitter has slightly higher output compared to the neutral white of the same LED. Why is that? Did a quick search and couldn't find the answer. Anyone?

 

[vivid]

It is always the case that a cool white emitter has slightly higher output compared to the neutral white of the same LED. Why is that? Did a quick search and couldn't find the answer. Anyone?

here is a great explanation. link

 

[strinq]

thanks vivid.
that was a superb answer by balou