Formal diplomacy — the official machinery: ministries (Nepal's Ministry of Foreign Affairs and its missions), ambassadors with credentials, treaties, notes verbales, démarches; the Vienna-regime rules (Unit 6).
Informal diplomacy — the unchannelled channels: Track II diplomacy (academics, retired officials, think tanks — the India-China-Nepal dialogue circuits; the Nepal–India Eminent Persons'Group (2016–2018) being the closest-studied Nepali example of semi-official track-diplomacy
producing recommendations on the 1950 treaty's future); Track 1.5 (officials and non-officials together); back-channels (the quiet negotiations that settled past crises); citizens' diplomacy, sports and cultural exchanges, sister-city twinning; the diaspora as informal diplomats. The exam's point: formal diplomacy is the law's realm; informal is the lubricant — outcomes often written in the corridor, formalized in the treaty.