Dear friend!
Please refer to the mapping between them:

As shown in the screenshot, the client signal is encapsulated into an OPUK signal after the OPUK-level overhead management byte is added.
Then, the ODUk-level overhead management byte is added to the ODUk signal. Then, the ODUk signal is encapsulated into the ODUk signal. After the overhead management bytes at the OTUK level are added, the signals are encapsulated into OTUK signals.

Overhead bytes occupy a small part of the signal flow and are negligible in the calculation rate.Therefore, you can see that the rate of OPUK is the same as that of ODUk and OTUK.
More: Rate summary of various service types.
Thank you!