All international flights arrive and depart from "Terminal A". However, some airlines physical check-in desks are located in "Terminal B". The different "terminals" are actually one big building and share a common airside and landside. If your international flight is listed as departing from "Terminal B" it just means that you check-in at desks located on the "Terminal B" side of the building and then walk to immigration and security checks in "Terminal A" to actually depart.