The Queen’s birthday celebrates the monarch of a country. Different countries celebrate on different dates and is adopted by each country by royal proclamations or statute laws.
The British Queen’s birthday celebrates the current monarch who reigns over many countries across the British Commonwealth and is celebrated on different days in many countries. It is typically not a day off of work or school.
Queen Elisabeth II birthday is celebrated on the 2nd Saturday in June in the UK. Dates vary for other countries within the commonwealth.