Reading list: What is the difference between an immigrant and a non-immigrant visa?
The difference between an immigrant and a non-immigrant visa lies in the purpose and duration of the stay:

Immigrant Visa:
An immigrant visa is for individuals who intend to move permanently to a country, typically to settle there. These visas are issued to people who have the intention of becoming a permanent resident, often based on family relationships, employment, or refugee status. The individual with an immigrant visa is expected to stay indefinitely.

Non-Immigrant Visa:
A non-immigrant visa is for temporary stays in a country. These visas are issued for individuals who plan to visit for specific reasons such as tourism, business, education, or medical treatment. The holder of a non-immigrant visa is required to leave the country once their authorized stay ends.

In summary, an immigrant visa leads to permanent residency, while a non-immigrant visa is for temporary stays.
https://eduprofound.com/immigrant-and-nonimmigrant-visas/