Airstrip One

Anyone out there who can explain this

Maybe my brain's switched off for the weekend, but according to this story:

They contain 15,000lb of fuel-air explosives, a variation on the deadly napalm which the US deployed with huge destructive effect - and to massive public outrage - in Vietnam.

Firstly is this actually true about it being "a variation on the deadly napalm"? Secondly if this is true why are Daisy Cutters not classified as chemical weapons?

I understand that the effect is explosive rather than chemical, but that could cover a multitude of sins. Please enlighten me.