Are passport photo sizes the same as US visa photo sizes?

Not the same. The photo required for a U.S. visa must be square with a white background, 5.1x5.1.

A U.S. visa is an endorsement by the United States on the passport or other travel document held by its own or foreign citizens to indicate that the holder is allowed to apply for entry into the United States. It can also be said to be an item issued to them. Endorsement certificate. U.S. visas can be divided into two categories: immigrant visas and non-immigrant visas, and each category can be divided into many subcategories.

Holding a U.S. visa does not necessarily guarantee successful entry into the United States. The U.S. Customs and Border Protection (CBP) will make the final decision on granting entry rights at the port.

On September 24, 2017, US President Trump signed the latest travel ban, adding 8 countries including Chad, North Korea, Venezuela, Iran, Somalia, Libya, Yemen and Syria to the new travel ban list superior.

The validity period of a U.S. visa refers to the period from the date of issuance of the visa to the period after which entry is allowed. Beyond this period, the visa is invalid. Generally, the United States issues entry visas that are valid for 3 months.