Fly Line Question

I recently bought an Orvis fly line to replace and old worn one. The
Old one was a 5 wt, wf, floater. The new line is a 6 wt, dt, floater.
When I put the new line on the reel it ended up too high in the arbor
causing rubbing. It was necessary to remove about 1/8" thickness of
backing to alleviate the problem. Both lines are Orvis' Wonderlines
for trout. Is the explanation that the 6 wt is "thicker"?