Omaha, Nebraska is 3.6 times larger than Rochester, New York.
Area: 342 km2 calculated
Omaha is the largest city in the state of Nebraska, United States, and is the county seat of Douglas County. It is located in the Midwestern United States on the Missouri River, about 10 miles north of the mouth of the Platte River. Wikipedia
Area: 96 km2 calculated
Rochester is a city in Monroe County, New York, south of Lake Ontario in the United States. Known as the World's Image Center, it was also once known as the Flour City, and more recently as The Flower City, annually hosting the Lilac Festival. It is the county seat for Monroe County. Wikipedia