What is the difference between a laptop computer, a portable computer and a notebook computer? My definition is that a laptop can be used comfortably on the user's lap or knees for extended periods of time. A portable computer is one that can be carried from A to B without too much trouble. A notebook is a computer that has a lid, with keyboard in the base of the casing and enclosed when shut by a hinged top that carries the LCD screen.
A decade ago, portable computers were rugged PCs with sturdy metal handles used by people who needed to compute in strange places. They came in beige-coloured, fibreglass or metal casings. The shapes were designed not for easy usage but for easy storage.
Portable does not always mean light. I have seen a technology company use one for sales demonstrations only recently. They simply update the motherboard inside and plug in an external keyboard and monitor.
The casing was chipped and marked but two of them fit nicely inside the cabin baggage restrictions adopted by most airlines, so it is easy to transport them.
They are also tough enough to be put through the mangler of the international check-on baggage system in most airports. They weigh up to eight kilograms each, certainly not in the lightweight category.
There are few true laptop computers still available.