[mcv]

X1 Carbon or X1 Extreme? They're two different laptops.

[basch]

For a brief moment in time it seemed like they were marketing the "X1Carbon" as the line and the Extreme as the sku variant. They have since dropped the Carbon. It also could have been new sources quoting press releases poorly.

Wikipedia also treats the Extreme as a submodel of X1Carbon. https://en.wikipedia.org/wiki/ThinkPad_X1_Carbon