Are immigrant and K visas the same?

No, immigrant and K visas are not the same. Immigrant visas are for individuals seeking permanent residency in the U.S., while K visas are non-immigrant visas specifically for fiancés (K-1) and spouses (K-3) of U.S. citizens, allowing them to enter the U.S. temporarily to marry or await permanent residency. The K visa holders must apply for a green card after marriage, whereas immigrant visa holders typically enter the U.S. as permanent residents.