These large organizations are always super confusing!
My understanding is that Deloitte Monitor sits within Strategy and Operations (S&O). Monitor was a classic strategy group acquisition a few years back that then got rolled into.
The view was that, S&O was more the management consulting practice, which could stand to benefit from a pure strategy group.
So, Deloitte Monitor is similar to Strategy& in PwC, EY Parthenon, etc.
Also, feel free to ask these questions during coffee chats or discussions with HR. They know thier organizations are complex and they appreciate you doing the due diligence to find out where you would best fit!