windows prores vs apple prores

I shoot 4K for several months and encode the files to prores hq 422 files on my windows system, upload them as 4K, but still sell only their HD versions. Recently I knew that some customers have requirements, the original Apple Prores encoder to be used.
I would be very grateful if someone explain me, whether exists any difference in the quality between Apple Prores and Windows Prores and does it really matter for customers?

There should be no difference between ProRes encoded on a windows machine vs an Apple machine. Apple holds the rights to ProRes, so even if you are encoding it on a Windows machine, the specification can still technically be considered "Apple ProRes". Also, 4k is still not desirable for many people, so they save money and purchase the HD version. If you look at Pond5's own stats, 4k sales only made up 3.38% of their sales this past month. (Just a little higher than their 720p sales for comparison)

Yes of course there is a difference! What I've seen so far ProRes422HQ on Windows through (entry level plugins) is still NOT that good as the original Apple ProRes422HQ rendered from a mac. Though there are some exceptions like RedCine-X and The Foundry Nuke but they have contracts with Apple. Thats why I do all my output rendering for stock agencies on a mac.

I really hope this will change because Apple is trying hard to degrade the mac platform to a dumbed down toyish i-OS.

PS. 4K is the way to go! Think of it as an investment. If you had a portfolio full of SD resolution clips you wouldn't sell them anymore or not that many of them. But if you were an early adopter of HD you still would have sales. Same is true for 4K material. It's better to have high quality material that is longer future proof.