Acrylic: These are liquid paints that are water soluable when wet but dry hard and waterproof. They are used for painting on the outside of hard plastic and metal items.
Enamel: Like acrylics, but oil based. You need white spirit or thinners to clean brushes. Better if the item will get regularly wet.
Polycarbonate: Special paint for use on clear model body shells, you paint it on the inside and it's flexible.
Revell 24898 X-Treme Quad...