Las Vegas is 2.9 times larger than Pasadena, Texas.
Area: 363 km2 calculated
Las Vegas, officially the City of Las Vegas and often known as simply Vegas, is the most populous city in the state of Nevada and the county seat of Clark County. Wikipedia
Area: 123 km2 calculated
Pasadena is a city in the U.S. state of Texas, within Houston–The Woodlands–Sugar Land metropolitan area. As of the 2010 U.S. Census, the city's population is 149,043 making it the seventeenth most populous city in the state of Texas as well as the second-largest city in Harris County. Wikipedia