Wikipedia's list of humorists are categorised as people who write or perform humorous material, but the article also states:
A humorist is usually distinct from a stand-up comedian.
Woody Allen and George Carlin are on this list—clearly, a stand-up comedian can also be a humorist.
There are various distinctions on the web.
Humorists typically receive higher pay.
This is ambiguous; one's salary does not define their job.
A humorist’s job is to make people laugh at important things.
Whilst I find this distinction more satisfactory, it's still open to debate: the importance of material is subjective.
How does one determine when a comedian is also a humorist?