I’ve gotten several comments deriding me referring to an Elizabeth Line station as “a tube station” but so far—despite my requests—nobody’s explained WHY.

Is it NOT considered part of the Underground?
It has the same logo but in purple, which I assumed was just for Queen reasons.

It interfaces WITH Underground stations, does it not??

Is this a colloquialism I just won’t understand?

@Graham_LRR maybe it's purple because it's a shiny station?
@CanvasWolfDoll @Graham_LRR Gonna need the ultra ball for that one

@Graham_LRR I believe the distinction is based on usage. The Elizabeth line is meant to be a commuter train or express regional rail service rather than a metro service that the tube is. I.e less stops, further apart

But I have mostly picked that up from watching Geoff Marshall videos and don't live anywhere near London so I'm not an expert

@Wearwolf @Graham_LRR Former UK resident here. Lived a few miles from London. Went to London multiple times.

Everyone I know used "The Tube" to describe the entire train system, not just specific lines.

Pedants gonna pedant.

@Graham_LRR it's considered rail because it uses the existing infrastructure of the Western and Eastern main lines. I'll grant that it's not helping it's case by being named like an underground line, and by using very similar iconography 😅
@Graham_LRR fionna: as an american who watches a lot of european transit youtube: crossrail was renamed the elizabeth line, it uses the same roundel but it's not "part of the underground". it’s. really silly, imo.
@Graham_LRR see also the DLR and the Overground and guess if they're considered part of the Underground. And the Cable Cars, if you want a real laugh.
@Graham_LRR I'll preface this with, no one should care enough to correct someone about it...
But purely to answer the question It's an overground line with some underground sections, so technically hybrid (and run by MTR rather than FTL if anyone cares). It's officially not part of the underground
@ramchale @Graham_LRR ah, so it’s not the Underground, it’s just Sparkling Metro
@Graham_LRR I’m a Londoner who would recommend @garius as a good person to ask about this. To give an uninformed answer, the Elizabeth Line, much like the Overground lines, does go through many tube stations but also mainline stations, so not all Elizabeth line stations will be tube stations. As a rule of thumb zone 1 Overground and Elizabeth line stations are tube stations, but outside of that they will have other names.
@Graham_LRR I can imagine that this is a subject on which even Londoners won't fully agree. My guess is that it's a "tube" if it's a train featured in the following video, and anything else isn't
https://www.youtube.com/watch?v=Hy7n7yTiE5M
Sounds of ALL Departing London Underground Trains

YouTube
@Graham_LRR As far as I can tell, people are REALLY INTO the Lizzie Line and keep treating it as a bit of a special part of the underground/a bit separate - but I live in the North not in London, so that's just an impression from talking to folks!

@Graham_LRR

It's a weird Londonism. Specifically, it's only a Tube Train if it if is literally short-curve-shaped to fit in a smaller tunnel. Since the Elizabeth Line takes full sized regular surface trains, it's not a tube train line.

And so Londoners have another way of spotting the outsiders.

@Graham_LRR Im curious about this as well because in Fallout London most stations are called "a tube station" but not all of them.
@Graham_LRR There's semantic quibles but broadly speaking the London Underground is run by Transport for London. The Elizabeth line was privatised for Thatcher based reasons.
@Graham_LRR It’s technically not part of the Underground, no. It’s a separate service. The reasons aren’t really important, it’s mostly just convention.
@Graham_LRR Different coloured roundels are used for different services - tube, bus, tram, riverboat - so the colour denotes it as its own thing. It’s not quite the tube as it’s using mainline stock that interchanges with both Tube and mainline stations - plus I suspect a desire to brand it separately for publicity.
@Graham_LRR I think simply for many "The Tube" is just The Underground proper. The Elizabeth Line is run by TfL and has a purple roundel, which makes it another of what TfL calls a mode, like Underground, DLR, Overground, Buses, etc.
Design standards

We have produced a range of design standards for use by staff, suppliers and design agencies involved in graphic design and layout.

Transport for London
@Graham_LRR Oh, re-reading, you're actually asking if it's not Underground -- yeah, it's not; the Elizabeth line is basically the east-west version of Thameslink. Other than being operated by TfL it's the same idea -- it uses regular Network Rail owned stations outside of the central part, you can use regular train tickets on it as you found, etc.
@rakslice OMG yes, thank you for this!!

@Graham_LRR In particular "Roundels" https://content.tfl.gov.uk/tfl-advertising-standard.pdf#page=8

Hmm... what is "TfL Rail" there? Well, it's actually a whole separate brand they created to use for the train services they were taking over that were going to become part of then Crossrail, for the 7 years before the central part was ready, presumably just so they could avoid spoiling the final brand before the whole line was ready
https://en.wikipedia.org/wiki/TfL_Rail

@Graham_LRR despite kind of being branded like a tube line with the purple roundel, it's considered a separate "mode" because it operates more like a traditional heavy rail line, though certainly at metro frequency. "The Tube" specifically refers to the underground lines with the tube-shaped tunnels - the DLR and Overground are not "tube lines" either. But definitely a pedantic Londoner thing.
To be fair most Londoners don't know or care to distinguish it either. It's like the Overground - the cost is the same, the concept is the same, the frequency is the same, so it's the tube 🤷‍♂️
@Graham_LRR The Elizabeth Line/Crossrail is a lot closer to the London Overground than the Underground/Tube. It’s actually part of the National Rail system (which is why your Eurail pass worked on it), not the Tube.
There were many people annoyed when the name was announced as the Elizabeth Line because it would lead to this confusion ([blank] line was previously reserved for tube lines)

@Graham_LRR it is literally not part of the underground, in much the same way that the long island railroad is not part of the New York subway. It’s part of the regular train network, aka network rail, just like Thameslink.

Why does it have the same branding? Because it’s run by TfL, who also run the overground, which is also not part of the underground, but which also uses the roundels.

It interchanges with some tube stations, but it also there’s loads of stations on the Elizabeth line that are well outside of underground territory. Lots of regular network rail stations also interchange with the tube.

There are technical reasons as well - tube trains all run on fourth rail 660V DC power, Liz line is 25kV overhead wires - but mostly, it’s a different service with different trains and different drivers.