Myanmar is 2 times larger than Vietnam.
Area: 676,578 km2 World Factbook
Population: 55,746,253 (July 2014) World Factbook
Burma, officially the Republic of the Union of Myanmar, commonly shortened to Myanmar, is a sovereign state in Southeast Asia bordered by Laos, Thailand, China, Bangladesh, and India. Wikipedia
Area: 331,210 km2 World Factbook
Population: 93,421,835 (July 2014) World Factbook
Vietnam, officially the Socialist Republic of Vietnam, is the easternmost country on the Indochina Peninsula in Southeast Asia. With an estimated 90.0 million inhabitants as of 2013, it is the world's 13th-most-populous country, and the eighth-most-populous Asian country. Wikipedia