Whaaaaat!? We got to the second page without a car analogy?!

Ok here it is:

Smartphone - city scooter - it's small, fast, you can escape the trafic, can park it where ever you want, it's fuel efficient.

Tablet - small car (Smart, Mini Cooper) - it's not as mobile as the scooter, but still small enough to park almost everywhere (even sideways), it's still very fuel efficient compared to the SUV, you can take a second person easily or some luggage, it's safer to be inside a vehicle in case of an accident.

Laptop - SUV - big, expensive, eats up a lot of fuel, it's difficult to drive it or park it in the city, but you can drive it even offroads, can transport 5 people and lots of luggage, very safe because of size.

But the book analogy is spot on anyways, because it shows exactly 1:1 the usecases.