Is OKR included in MBO?

I've read How Google Works.
And now I'm interested in OKR (Objective and Key Results), which is explained in this book. It is really similar to MBO (Management By Objective). I'm learning MBO for five years, and I feel that OKR might give me good hints to understand MBO.

In my understanding, OKR is one of the method to execute MBO. In other words, MBO is theory and OKR is operation. Here I will explain my opinion:

MBO explains its aim and why MBO itself can be solution, based on psychology and experience. It lets player to be professional, excited and motivated. But there are many abstract things in its definition (e.g. ), so MBO player need experience to improve how to execute. MBO is a theory and framework, we need to improve our system and operation step-by-step.

OKR provides many concrete definitions and operations (how key results should be, how to score, what is ideal result etc.), so it's easy to adapt to real business. It is also easy to scale, so it suits for big companies. But I feel that it focuses on operation too much, and it is easy to forget about why we should do so easily.