What's the difference ?

[Kenworth]

like everyone else has stated the difference in name and engine sound also the fact that the boxville's number plates are backwards..
that is all 

[Spekter]

boxville sounds for girls, just buy the boxburg. 

Real men use Yankee.

[Deff]

Maybe in height ?

[Tropie.]

Maybe in height ?

Hell, NO.

[Marius]

Maybe in height ?

Hell, NO.

Aaa aa aa , the colour xD

[themooody]

Left = Boxville
Right = Boxburg

Name left = The_Boeing767
Name right = The_Spinner (my friend)

nice one

[deejayy2k]

from here http://gta.wikia.com/Boxville

"GTA San Andreas features a specialized variant of the Boxville, referred officially as a Boxville, named internally in game files as a "boxburg" (a possible short form of "Boxville Burglary"), and unofficially dubbed the "Boxville Black" or "Black Boxville". Its difference from a standard Boxville include its unique dark gray body color and a quieter engine (using the same engine audio same as a Pony)"

also if you look in the official strategy guide (yes i actually bought one) there is no boxburg just boxville and boxville(black)