Write-fag wanting to be accurate, has a question about White Phosphorus versus Smoke grenades.

Scene, tense brawl with a couple of strong guys getting 'stuck in' and a weaker guy hiding nearby. Weakling offers to help, says he's got something non-lethal to help out and chucks a couple of smoke bombs into a mass of mooks, away from his buddies.

The scene idea was that one of the guys with military experience realizes almost instantly what the noob did and shouts "YOU IDIOT!!! That wasn't a smoke grenade! That was WILLY PETE!!!" And the noob gets the horrified look as screaming comes out of the smoke cloud.

So, off the top of people's heads, what's the difference between a WP grenade and a smoker?
>Color of the gas
>sound of the hiss as it escapes
>one cloud will look thicker than the other
>the grenades themselves look different
>etc