Phuket to Koh Samui

Yes. Bangkok Airways flies the route nonstop seven to eight times a day, taking about 55 minutes, with departures from roughly 07:30 to 19:30. It's the only airline on the route (it owns Samui's airport), so fares run ฿1,900–3,500 rather than budget-carrier prices, with a checked bag included.

Bus or van across the peninsula to the Surat Thani coast, then a ferry. Lomprayah's through-ticket (coach + fast catamaran) leaves Phuket between 07:30 and 10:00 depending on pickup option, costs ฿1,300–1,650, and arrives at Samui's Nathon pier around 15:45. Budget combos via the Donsak car ferries run ฿555–780 and take 9–10 hours.

55 minutes in the air (about 3 hours door to door with airport time), versus 7–10 hours overland depending on the combo. The islands are on opposite coasts, so there's no shortcut between those two numbers.

Flying: ฿1,900–3,500 one-way booked ahead on Bangkok Airways. Overland: ฿1,300–1,650 for Lomprayah's bus-and-catamaran through-ticket, ฿780 for the Phantip combo, or about ฿555 for the cheapest bus-bus-ferry stack. On promo-fare days the flight can cost barely ฿700 more than Lomprayah, so check both before defaulting to the long day.

Only by air. Every overland through-service departs Phuket by about 10:00 so it can make the afternoon ferries, and the last Lomprayah pickup is the 10:00 airport departure. After that window, your choices are an afternoon or evening flight, or staying the night and starting early.

Fly, for most itineraries: Bangkok Airways' 55-minute nonstop (฿1,900–3,500) saves six to nine hours over the overland day, and the fare includes a checked bag. I'd go overland only if the budget genuinely demands it. Lomprayah's ฿1,300–1,650 bus-and-catamaran through-ticket with hotel pickup is the comfortable version, arriving at Nathon pier around 15:45.

About 55 minutes gate to gate on Bangkok Airways' turboprops. Call it 3 hours door to door with airport time at both ends. There are 7–8 departures a day between roughly 07:30 and 19:30, all nonstop, and connecting via Bangkok (5.5–12 hours) only makes sense when the direct flight is sold out.

Not a direct one. Phuket is on the Andaman coast and Samui is in the Gulf of Thailand, on the far side of the peninsula. What's sold as the 'Phuket to Koh Samui ferry' is a bus or coach across to the Surat Thani coast followed by a Lomprayah catamaran or a Donsak car ferry: ฿555–1,650 and 7–10 hours in total, all departing Phuket by about 10am.