Short answer
The cost of living in the Azores is generally lower than in Lisbon or Porto but higher than in most of mainland Portugal, mainly because many goods are shipped in. Housing, groceries and transport are the biggest variables, and prices vary between islands and between Ponta Delgada and smaller towns. For current figures, check local listings and official statistics rather than relying on fixed numbers.
General information, not legal or tax advice. Rules and amounts change: confirm with official sources.