iOS 9 preinstalled better than upgrade?

[Racineur]

Hello, I wish to give an Apple companion to my iMac instead of my old Galaxy Tab 3 (that works like a charm by the way but is very much an Android device with all its bizarre things). My point is: the Mini 4 caught my attention cause iOS9 comes preinstalled. I like that. But after reading all the posts, seems that I should not elude the question being "Maybe I should buy an Air 2 instead". What tickles me is the fact that an Air 2 would come with iOS 8 and I would have to upgrade. Is there a difference between a preinstalled OS and one that is installed by upgrading. I mean microscopic bits and pieces. To me, a Mini 4 with preinstalled iOS 9 is like wiping clean the disk before installing a new system. Am I wrong? Is this important before making the decision to buy one or the other? After that, I'll probably feel for an iPhone. Yep, stuck with an HTC now.
Thanks for giving me cues.
Racineur in Montréal.

 

[v04bvs]

You can easily perform restore on your iOS 8 device. It will do completely clean install of iOS 9 and it won't have any difference to preinstalled iOS 9.

 

[Shirtin]

You can easily perform restore on your iOS 8 device. It will do completely clean install of iOS 9 and it won't have any difference to preinstalled iOS 9.

Why do that when you can upgrade first to iOS 9 and then do a restore?

 

[RockSpider]

I'd say the Mini 4 was built with IOS 9 in mind so there could be a chip or two upgraded to take advantage of it, but that's only a guess based on years of buying and building computers.
A clean install on the Air will give you just that, a clean OS based on a very capable iPad but maybe not built with IOS 9 in mind.
And hey, don't rubbish HTC, I have the HTC M8, a more than capable phone, but I've had it 12 months so looking at either the new Sony Experia Z5 or one of the new Windows phones.