alt Hacker NewsBecause entry is handled by CBP - Customs and Border Protection.
Immigration - which is the process of becoming a US permanent resident and/or citizen - is handled (mostly) by USCIS.
Other visas are handled by the State Department (foreign ministry).
Not an expert, but this is my understanding.
My understanding is that immigration gets you in the country, even as a tourist, and customs gets your stuff in.