Depends on what part of the country you live in lol..... Check out this link to a previous discussion of mine "your biggest tanker?" where this exact issue is discussed.
tankers are airplanes while tenders are road vehicles. however if you are applying fore a federal grant and they ask for your water source the only thing they have on there is tanker
I prefer Chief Brunacini's interpretation. There are far more trucks with tanks than there are aircraft. Instead of changing the road vehicle name, call the one's that fly; "BADLOW, Big Aircraft Dropping Lots Of Water."