They're an hour apart and often visited together, but Abu Dhabi and Dubai have genuinely different characters worth understanding before you book.
Dubai is louder, taller and more overtly built for tourism — the record-breaking towers, the beach clubs, the retail spectacle. Abu Dhabi, as the UAE's capital, carries a calmer, more institutional tone: government buildings, national museums, and a Corniche that feels more like a civic space than a tourist strip. Neither is objectively better; they suit different trip styles.
Abu Dhabi's strengths are cultural heavyweight sites (Sheikh Zayed Grand Mosque, Louvre Abu Dhabi, Qasr Al Watan), the concentrated entertainment of Yas Island, and generally quieter beaches on Saadiyat Island. Dubai's strengths are its skyline, its shopping and nightlife scene, and its sheer density of headline attractions within a smaller area.
Because the drive between the two city centres is roughly 60–90 minutes, many visitors base themselves in one and day-trip to the other, or split a week roughly in half. If culture and theme parks matter more to you, weight your nights toward Abu Dhabi; if nightlife and shopping matter more, weight them toward Dubai.
Yes — it's a common itinerary. With an early start you can comfortably cover Sheikh Zayed Grand Mosque and either the Louvre Abu Dhabi or a Yas Island theme park in a single day.