link between Category/Subcat/item & Service catalog Categories.

Hello

We are in the process of

reorganizing our Categories
creating a service catalog
and implementing ITIL incident & reuqest management with SD+

Can someone please explain me the link (if there is one) between Category/Subcat/item & Service catalog Categories. Here at the screenshots to show what I mean:

How can I use those field to the mentionned ITIL processes, knowing that problem and change management will follow afterwards?

If there is NO link between Category/Subcat/item & service catalog categories will it change in the coming releases?

Do I miss something?

Thanks A LOT for for your help.

Best regards, Marc