What is the biggest difference in Johnny Walker red, black, green, and white label besides price?

I've only ever had red and black.  Red is a decent upper mid-grade scotch (it's even what I was trying when I quite suddenly developed a taste for scotch).  Black is nice and smooth.  I don't know about green or white, but there is blue label, and my brother tried it, says it's not worth the difference in price.

As a card-carrying member of the Striding Man society, I can tell you that there's no white label.  There's a gold label.

Red: entry-label blended Scotch; best used for mixing cocktails.  

Black: good utility Scotch for everyday drinking.

Green: If you like that peaty/smoky/peppery types of blends this is the way to go.

Gold: Less peaty, slightly sweeter finish, lighter colour than black/green.

red - Not good even with cola

black - Decent for the price

green - Good but overpriced

white - Have not had it

blue - Out of my budget

Red should be avoided, Johnnie Walker Double Black is as low as you should sink with their range, the others, upper-shelf, whatever, you barely notice the difference.