Dutch has clear register differences. Formal (formeel) vocabulary appears in official documents, business writing, and news. Informal (informeel) vocabulary is used in conversation, text messages, and among friends. The same idea often has two words: overlijden (formal: to pass away) vs doodgaan (informal: to die); aankomen (formal: to arrive) vs komen (informal: to come).
More formal/informal pairs: woning (formal: dwelling/home) vs huis (informal: house); voertuig (formal: vehicle) vs auto/fiets (informal); aanvangen (formal: to commence) vs beginnen (informal: to start); verzoeken (formal: to request) vs vragen (informal: to ask); zich bevinden (formal: to be located) vs zijn (informal: to be).
Register in writing: formal documents use volzinnen (complete sentences), geen afkortingen (no abbreviations), and avoid umgangssprachliche (colloquial) terms. Emails to companies often start with Geachte heer/mevrouw (Dear Sir/Madam) vs Hoi or Dag (Hi) to friends. Knowing the appropriate register prevents social and professional misunderstandings.