The term "Kaiju," which means "strange beast" or "monster" in Japanese, originated in Japanese folklore and mythology. It has been used for centuries to describe various mythical creatures and monsters.
Godzilla, on the other hand, is a specific character that first appeared in the 1954 film "Godzilla" (Gojira) directed by Ishirō Honda. The character was created as a part of modern Japanese pop culture, specifically within the genre of kaiju films.
So, while Godzilla is a prominent and iconic kaiju, the concept of kaiju as monstrous beings predates Godzilla by a considerable margin. (Chat GPT)