For all things 180/185 check out
http://www.skywagon.com/skywagons.html
click on the "model changes"

Both the 180 and 185 have narrower cabins than the 182. Neither the
180 or 185 have a rear full height cargo door (something the 206 has).
But the 206 doesn't have a copilot door. Both the 180 and 185 have the
"jack screw" trim (on the floor) as opposed to a "trim tab". Both the
180 and 185 have manual flaps. The models evolved over the years,
bigger better engines, slightly differnt wings and modern (basic six)
panels.

Early Cessna 182's were narrower than the later models, and the early
182's had the "jack screw" trim and manual flaps. The early 182's were
a nosewheel version of the 180, but after they changed the 182 to the
modern config, it got a wider cabin, different trim and electric flaps
so the differences grew over time.

The 206 is larger and will hold large cargo. It is substantially
easier to load and unload. It has a nosewheel of course. If fitted
with the STC's copilot door, it is the most desirable small
charter/freight airplane up north.