Here's one of the oddities of the airline industry, when seen from a mainstream common-sense viewpoint: the fact that 'direct flights' and 'non-stop flights' don't mean the same thing.
Yes, they should... and the use of two terms which are nearly identical in everyday language to mean two quite different things can be quite confusing.
So what's the difference?
Non-stop vs direct
A 'non-stop' flight means exactly what you'd expect: the flight goes from one destination to another without stopping.
But wait – isn't that the same as a direct flight, which by definition goes directly from A to B?
You'd think so... but in airline-speak, a 'direct' flight can actually mean there's at least one stop-over along the way.
Yes, that makes no sense at all: you're not flying direct because you're stopping somewhere en route.
But in the argot of aviation, as long as the flight has the same flight number it can break its journey – easily adding up to two hours to your total travel time – and still be considered a 'direct' flight.
Here's a practical example: Singapore Airlines flights between Singapore and San Francisco.
The Star Alliance member recently launched non-stop flights on this route, using an Airbus A350: the plane takes off from Singapore's Changi Airport and doesn't touch down again until it reaches San Fran.
Singapore Airlines also has a Singapore-San Francisco service which stops off at Hong Kong en route: this is categorised as a 'direct' flight, with both legs carrying the same SQ1 or SQ2 flight number. (Passengers can also leave or join the flight at that Hong Kong stopover.)
Adding one more wrinkle to this are 'connecting flights', although happily these are pretty much what the name indicates: you'll actually change flights (and flight numbers, and aircraft) partway along your journey.
That's most common at large hub airports, such as Singapore, Hong Kong and Dubai: for example, most Emirates' flights from Australia to Europe require changing to a connecting flight at Dubai.
Plain English spoken here
However, you can rest a little easier when reading articles on Australian Business Traveller:
In keeping with our focus on the mainstream and the passenger, we use 'direct' and 'non-stop' in the only way that makes sense to most people and thus most of our readers – as plainly descriptive, interchangeable terms.
When a route has a stop-over, we clearly call that out.
But the nonsense of talking up a 'direct' flight when it actually has a stop-over along the way – when it's thus not really direct – is a confusion you don't need to worry about, because we won't subject you to it.