CDL Commercial Driver's Liscense
Needed to drive a bus, limo, dump truck, weights over 19k combined, etc., etc., etc.

Hazmat Endorsement:
Lets you transport hazardous or semi-hazardous materials legally. It mostly deals with accidents and how they need to be treated if something happens. Placards for displaying what you are carring and of course the lovely paper trail of what was/is shipped. From corosives, flamables, oxidizers and radioactive matrerials are all needing a Hazmat Endorsement.