Enby (from NB, from non-binary) is kind of an umbrella term to refer to anyone who doesn’t strictly identify with one of the binary genders (male/female). Agender would certainly fall in that category, as would other identities such as genderfluid, pangender, and many more. There are also plenty of people who don’t want and/or care to have a more specific label, and just refer to themselves as non-binary, full stop.

To the best of my understanding, genderqueer is also an umbrella term which means pretty much the same thing as non-binary, but has a somewhat more “radical” nonconformist connotation. There is significant overlap between the two terms and whether someone identifies with one term or the other or both is pretty subjective. Is agender genderqueer? If you identify with both terms, then it is :)