What's the difference between "back office" and "middle office"?

Maybe I’m just naive (most of my career spent in industry working in corporate finance) but can someone tell me in a few sentences or less what the differences are between “back office” and “middle office”. Responses are greatly appreciated, thanks.

From my understanding back office is where you have no contact with clients or trading desks, IE P&S, The cage etc… Middle office is where you help the traders or clients directly, IE Trade support. More opportunity to get client facing or trading role when you deal w clients or traders directly.

Back offices do behind-the-scenes work like trade clearing, calculating settlements, looking at documents, etc. Middle office people, as mentioned above, work directly with traders or counterparties. At my desk, they are in charge of market inputs (get from third parties or using data services), P&L calculations, trade entry approval, and misc. duties that help the front office. Middle office people generally have longer hours than back office people. However, they also have more chances for upward mobility since they have more interactions with people with decision making ability.

Pretty much what Walrus has said. Back Office: Where settlement of trades made by Front Office is done. Middle Office: Where Policy decisions are made for Trades (Front Office) and Settlements (Back Office). For Example, placing limits on traders, currencies, countries etc, setting up the approval process for trades and settlements etc.

Thank you guys for the helpful comments.