There are many different types of protected areas across the world. The IUCN (International Union for Conservation of Nature) has split them into six categories. Even though the IUCN call category II 'National Parks', the UKs national parks are actually in category V.
A protected area managed mainly for science or wilderness protection
Denali National Park and Preserve, USA.
© Frank Kovalchek
A protected area managed mainly for ecosystem protection and recreation.
Mu Ko Ang Thong National Park, Thailand.
© Jason Ellsworth-Aults
A protected area managed mainly for conservation of specific, unique natural features.
Owachomo Bridge, Natural Bridges National Monument, USA.
© Paul Kelly
A protected area managed mainly to preserve specific species and to maintain habitats
Young Gator at Lake Woodruff Wildlife Refuge, USA.
© Andrea Westmoreland
A protected area managed mainly for landscape/seascape protection and recreation.
Cairngorms National Park, UK.
© Bruce McAdam