They are and they are not. Thymol is a much more concentrated version of the chemical that can be derived from thyme. It is also found in other mints as well.
Whether or not thyme oil as an essential oil is as effective as the concentrated thymol, I wouldn't know? I think that some have assumed that they are one in the same since thymol is derived from thyme, but whether it has been actually proven to be as effective or not and presented or published is another question. I haven't personally seen or heard of any documented proof of it.
"Success is not final, failure is not fatal: it is the courage to continue that counts." Winston Churchill