NON at all!
Same railway two different names!
Do you need help with your history project about slaves travelling to freedom or help in transportation provided by a train system that operates under the surface.of the street.
In London, some of the underground mass transit railways ("Metro" or "Subways" elsewhere) have a tubular tunnel shape, hence they gained the nickname of "the tube".
An underground railway could be any type of subterranean railway. A 'tube' is so named because of the shape of the tunnel.
Semantics. In the US an underground passenger railway is referred to as a 'subway.' From what I gather the British term is 'tube,' but they are both the same thing.
Further, the person at the controls of a subway or other electrified railway above ground in the US is the 'motor man.'
Above ground on non-electrified lines the person operating the train is called a 'locomotive engineer' or just 'engineer,' whereas in the UK and elsewhere within the British influence the person is referred to as train 'driver.'
As has been said we Yanks and the British are two people separated by a common language...
A 'tube' is a kind of underground railway which runs in a tunnel with a circular cross-section, usually because it has been bored with a tunnel boring machine which resembles a giant drill, producing a circular-section tunnel.
Other underground railways with tunnels dug by other means may have tunnels with a square or rectangular cross-section. These may be old tunnels dug manually by navies with shovels, or ones close to the surface made by 'cut-and-cover': digging a large trench then roofing it over again, usually to take advantage of the value of the surface thus created.
In London, England, people sometimes refer to the whole underground railway system as 'The Tube' although in fact not all the lines are tube type, and others use the same term to mean only the tube lines. This can be confusing.
Same thing in London. Its formal name is The London Underground even though outside of central London, a lot of it is not actually underground.