Kelvin temp & Nm spectrum

Can somebody explain to me in short why the Kelvin temp of the LED lights matter if they are full spectrum in nm mesurement ?
And what is the difference?
And what is the best In LED light Cobs and QBs 3000k/3500k/4000k/5000k for growing quality buds?

I always thought that the 2700k lights or warm red what have you,were for flowering and the 6500k blue lights for veg.

Alot of my knowledge seems out dated and i am trying to learn everything again from scratch,sorry For all the questions.

(Very baked)

They'll all veg and flower.
Most people seem to go with 2700k - 3500k for flowering.
Ive used 3000k - 4000k for vegging and flowering.
I've a few mixed spectrum boards - 3000k 90cri + 5000k 80cri that veg and flower good too.
There's probably too much blue in the 5000k and above for flowering on its own but I haven't tried it.
This has been my experience, other people's experiences may vary slightly.