Ranchers are basically larger displacement versions of their smaller "homeowner" grade cousins.
I am not as familiar with all the new/current 500 series saws as I am the 300 series, so I will use the 300 series as my example. (I'm sure they have their 500 series counterparts though)
You had the 340, 345, and 350.. All had plastic crankcases and not pushing the power per CC that the XP line does. Then comes in the "Rancher" saws. For several years it was the 455 alone. Same type of construction as the 340, 345, and 350 with 5cc more displacement. (and less power than a 346xp). And 3 or 4 years ago (ready to be corrected by Mr. Troll if needed) they decided the line-up needed a still bigger version and hence the 460 Rancher. Comparing to the smaller 40-50cc non-XP saws, the Ranchers are very similar if not virtually identical in construction and features, only bigger.
And not to confuse the issue even more, Husky had/has a class of saws in between these "homeowner" grade and pro-grade XP's.. The 359, 570, and 365 come to mind in this case. (I would also say 353 was in here too, but I do not recall if they had plastic cases or mag.) While still not quite making the power (on paper) that their similarly sized XP counterparts do, they do sport the better construction and features like magnesium crankcases, more adjustable oilers etc.. These saws make better power for their sizes than a homeowner grade saw.All of these classes are reflected in the price point.. You can buy a 460 Rancher for what, $400 new?? And the similarly sized 562XP will run you 7 bills most places... Both 60cc saws, but VERY different in construction and performance level.
There are your 2 main classes aside from the XP's and how the Ranchers fit in.
I'm not sure where the 235/240 fit in... Occasional use perhaps???
FTR: it's my opinion that Husky/Johnny-Red's, Dolmar, and Echo's model designation system is MUCH easier to understand than Stihl's.. Not hating on Stihl, it's just that if I see and ms290 (for example) I haven't a clue as to engine size or pro-grade vs non-pro-grade...