Oral or Verbal?

I've often wondered this. Newsroom101.com explains.

We don't have a written contract, but we have (an oral one, a verbal one).

The correct answer is "oral".

Both written and spoken contracts are verbal because both involve words. So
"oral" and "verbal" aren't interchangeable. Oral is the opposite of
written.What's the opposite of verbal communication? Nonverbal. No words.