The key difference from the Fortuner is the open cargo bed instead of a third row of seats. This is a completely different use case: surfboards, suitcases, bulky items and wet diving gear, in other words everything you would rather not carry inside the cabin. The cargo bed can be washed out with a hose.
The Hilux has the same off road ability as the Fortuner. It offers high ground clearance, ladder frame construction and a diesel engine with strong torque. Descents to beaches and climbs to hill villas are routine for this vehicle.
Fuel use is about 8.5 to 9.5 litres per 100 km, slightly less than the Fortuner because the Hilux is lighter.
Please note that the cargo bed is open to the weather. If you carry items that must stay dry, bring a cover or waterproof bags, because rain in Phuket can start within five minutes.