expense items vs inventory expense items

Hello

need your help, i found this somewhere on the internet , for expense items and inventory expense items (see below)

now my question on this:

-for expense items, there is nothing to be tracked , and their destination type is expense (normally month end accrual ) --> so this is ok, I understand, (eg if you buy pencils, or services or ...)

but I was wondering in which scenario you would use the inventory expense item ?  when you set it up llike below, they are received in inventory in eg a non asset subinventory --> would this subinventory then need to be quantity tracked or not ? and what would be the difference if quantity tracked .. vs non quantity tracked on subinventory creation for my inventory expense item.