Luxury cruises

What are the differences between a luxury cruise and a standard cruise? → Luxury cruise line focus - Windstar → Luxury cruise line focus - Ponant → Luxury cruise line focus - Regent Seven Seas → Luxury cruise line focus - Seabourn → Luxury cruise line focus - Silversea → Luxury cruise line focus - Seadream → Luxury cruise line focus - Crystal Cruises → Luxury cruise line focus - Star Clippers →