I have been using the Qiskit aqua QuantumInstance for a while, and have recently discovered the IBMQJobManager class and the two seem to be quite similar. Are there differences between them? Will they be consolidated together in the future?
By looking at the documentation for the two, it actually seems the two have quite different objectives, here is a brief summary: the quantum instance is mostly used to control the transpilation and execution of a circuit via many different parameters, such as the backend, for simulation the noise model, basis gates, coupling map, etc., and is quite useful when wanting to run an Aqua algorithm on the particular instance.
As for the IBMQJobManager, as said in the documentation, the main objective is to handle jobs and pulse schedules in order to be able to run them on backend and then rebuild them as fitted.
Do you need a specific detail more explained? If so please tell me and I'll try to detail it more :)