Founder of interviewing.io here.

A few differences. We do mock interviews. Other Branch doesn't (at least not yet). Otherbranch has one very good standardized assessment that they use (like the early Triplebyte one). Our way of assessing candidates is by aggregating mock interview performance (and doing some stuff to correct for interviewer strictness etc). Basically people come to us for mocks and stay for the jobs (if they do well enough in mocks).

We both do hiring, but OtherBranch focuses on a different type of employer: earlier stage startups, and we tend to focus more on hiring for later stage ones/FAANGs/FAANG adjacents.