These 3 days are similar and different but all holidays in the USA.
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1. Patriots Day is every 3rd Monday in April and celebrates the early battles in the War of Independence.
It's celebrated primarily in Wisconsin and Massachusetts. Read the book on Gif Lingua books.
2. Patriot Day is the common name for the commemoration of the 9/11 terrorist attack. It is formally known as the National Day of Service and Remembrance.
3. Memorial Day is a federal holiday in the United States for remembering the people who died while serving in the country's armed forces. It's the last Monday in May.