You obtain an immigration status in the U.S. through admission at a port of entry or by approval of an application to USCIS. Your status is also referred to as “visa status” or “nonimmigrant status”. A visa is an entry document only. You can have more than one entry visa in your passport (Canadians are exempt from the visa requirement) but you can enter the U.S. in only one status.
The status in which you are admitted by an immigration officer is stamped in your passport and recorded electronically if entering by air. Land borders issue a paper I-94 record. If your status is approved by USCIS as a change from another status, your I-94 card will be part of the USCIS approval notice (I-797 Notice of Action form).