Yes, JP8 is not very heavy, but this is the lingo in the industry as compared to gasoline.

Biodiesel, as referred to in the US, is usually B100, 100% soy methyl ester. Various blends with regular auto diesel are available B2, B11, etc.. Other base oils are also used, canola or corn most commonly. The Wikipedia page has good info.

http://en.wikipedia.org/wiki/Biodiesel