Inconsistency for Gmail and Exchange in Mail.app My Mail.app is configured for Gmail and Exchange.



The Exchange shows subfolders directly inside Inbox, but Gmail has separate Googletab below Mailboxes tab.



Why does Mail.app show subfolders in different places? Is it possible to make it consistent (preferable like for Exchange)?

MacOS version is Sierra.
Mail.app just mimics whatever structure is defined on the respective mail server. In Gmail folders are just labels (or saved searches for labels) so they show up outside of Inbox (as do iCloud folders actually, even though those are not searches). 

If you want to unify the way folders are represented you probably should checker whether Exchange allows to create folders outside of Inbox.