Comment by YZF

I edited my reply because it is sometimes referred to as both. But hey, can't rob you of the joy of correcting someone on the Internet.

https://www.uscis.gov/working-in-the-united-states/temporary...

"If you are a Canadian citizen, then you are not required to apply for a TN visa at a U.S. consulate.

You may establish eligibility for TN classification at the time you seek admission to the United States by presenting required documentation to a U.S. Customs and Border Protection (CBP) officer at certain CBP-designated U.S. ports of entry or at a designated pre-clearance/pre-flight inspection station. You must provide the following documentation to the CBP officer:"

"You may be eligible for TN nonimmigrant status, if:

    You are a citizen of Canada or Mexico;
    Your profession qualifies under the regulations;
    The position in the United States requires a NAFTA professional;
    You have a prearranged full-time or part-time job with a U.S. employer (but not self-employment - see documentation required below); and
    You have the qualifications to practice in the profession in question."

"If a CBP officer finds you eligible for admission, you will be admitted as a TN nonimmigrant. "

The main point is this has none of the process usually related to "visas" and even if that term is sometimes used along with "TN status" it's its own special thing. Canadians don't need a Visa to visit the US and I am not a lawyer. Mexicans might be in a slightly different situation. Either way, the proper legal answer has no influence whatsoever on the points being made.