Prospect Park (Brooklyn) is 40% larger than Hyde Park, London.
Area: 1 km2 calculated
Hyde Park is one of the largest parks in London, and one of the Royal Parks of London, famous for its Speakers' Corner. The park was the site of the Great Exhibition of 1851, for which the Crystal Palace was designed by Joseph Paxton. Wikipedia
Area: 2 km2 calculated
Prospect Park is a 585 acres public park in the New York City borough of Brooklyn located between Park Slope, Prospect-Lefferts Gardens, Ditmas Park, Windsor Terrace and Flatbush Avenue, Grand Army Plaza and the Brooklyn Botanic Garden. Wikipedia