Ok,

I know that when you want to flash a k-series phone to w-series, you lose like half the phone! what i want to know is, why?

Because they are very different is about the simplest answer you'll get.

It dependes on what K you flash into what W.
ETC, you doesn't loose anything on K750@W800, but on K800@W880 you loose joystick, camera, irda...

Well i know that, but why DO you lose it?

Because it's completely different hardware and firmware.
That IS the answer.

It's simple programing it was made for completely different hardware

But can't you still use the same drivers, ie on K750@W800 having K750 drivers instead of the W800 ones?

No. The keypad for one is totally different.

Well a very inaccurate but correct way of putting the question suthi posted would be...
If you've got a camera and flash it with MP3 player firmware, why can't you take photos?
I believe the answers given are substantial

oh, i guess that helps me understand, thanks =]

Here are the list of compatible firmwares
http://forums.se-nse.net/index.php?showtopic=21943

W800 was the a complete copy of K750I Becouse K750I had the best thing on the market and was the biggest seller They made a copy from k750i and tought ppl wouldn't notice and many didn't

But K750 is more stylish than W800, W800 looks like a toy.

It looks like a walkman.

Also a toy, K750 looks much more betta.

A bit too much  eh?

How about from K to "C"

That's more like it