Fiji is 24 times larger than Tonga.
Area: 18,274 km2 World Factbook
Population: 903,207 (July 2014) World Factbook
An island nation in the South Pacific Ocean east of Vanuatu, west of Tonga and south of Tuvalu. The country occupies an archipelago of about 322 islands, of which 106 are permanently inhabited, and 522 islets. The two major islands, Viti Levu and Vanua Levu, account for 87% of the population. Wikipedia
Area: 747 km2 World Factbook
Population: 106,440 (July 2014) World Factbook
Tonga, officially the Kingdom of Tonga, is a Polynesian sovereign state and archipelago comprising 176 islands with a surface area of about 750 square kilometres scattered over 700,000 square kilometres of the southern Pacific Ocean, of which 52 are inhabited by its 103,000 people. Wikipedia