Aww, no fins on the chainsaw?
To be honest, I'm not partial to the mower with fin's look, However, the top ones restoration is very well done, and suits the style.
Also, while I am not really into the look, I can see it's value as a collectable, In fact, things like 'Ugly' make some mowers more collectable, Like the Victa Vortex, Ugly tranlates to Unique!
Wings only work sometimes, Valliant S-Series pulls off wings beautifully, This mower does not, but you could say it's Beatufully Ugly!

Emmo, I'm guessing the differences are due to changes made for different years, although there is every possibility this mower was offered with a choice of engine.
As for the cup starter, I have seen it a few times, I beleve it was seen on some engines that came with a recoil-starter option, as this cup could be engaged by the right kind of starter, therefore the only change needed to fit a recoul strter would be to punch/drill out the mounting holes, saving the manufacturer the cost of making two different starter attachments.