Obviously, different circuits, but which one handles which function?

Thanks so much

Joe

 

I'll give the HS level explanation. 5 is too hard because you need to explain electronics using easter bunnies and oatmeal cookies.

The BMS is usually directly tied to the batteries internal cells at all times. WIth most commercial batteries that need a BMS, you won't see it, as it's inside the battery case. It protects the cells from under charge, over charge, imbalance between cells and various dangerous or harmful battery cell conditions and can provide information about the current charge condition of each cell and the battery as a whole.
https://www.allaboutcircuits.com/technical-articles/introduction-to-battery-management-systems/

Nowadays, Li-ion batteries reign supreme, with energy densities up to 265 Wh/kg. They do, however, have a reputation of occasionally bursting and burning all that energy should they experience excessive stress. This is why they often require battery management systems (BMSs) to keep them under control.

In this article, we'll discuss the basics of the BMS concept and go over a few foundational parts that make up the typical BMS.

The charger/charge controller is the device that actually sends electrical energy to the battery for storage. The charge controller is designed to safely and completely charge the types of batteries it was designed for, using the electrical energy supplied by a utility powered charger (that might be included in the charge controller), gas generator or other energy source like solar panels.