There is no difference. Because Oceania is the name of the pacific region that Melenesia, Polynesian&Micronesia are in. Micronesia is above the equator while Melenesia is just below Micronesia and Polynesia lay to the east of Melenesia. All these islands and people of these 3 region share the same ancestral roots which is Austronesians. People of Micronesia in the Islands of Guam, Saipan, FSM and Marshalls have a Compact of Free association with the U.S. These islands are which i named are semi U.S territories and and use the American dollar. Guam on the other hand is a US territory while Saipan is a commonwealth. The Micronesian islands of Nauru and Kiribatti are under Australian protection and use Aussi money. Melenesia is under the protection of Australia. Polynesia is divided between the US and France
