It looks like a minor difference, but the former one has segoe ui before helvetica (which is hard-coded as Arial alias on Windows), so it would use segoe ui on Windows; while the latter (currently using) one would show the content as Arial on Windows.
There was a time when Helvetica crapped out spectacularly in Windows with a certain combination of user-installed fonts. Can't remember exactly which combination it was or perhaps still is, but anyway that was a pretty solid reason for prioritizing Windows default fonts over Helvetica. Maybe someone pointed that out to the author who changed the content but didn't really test it on their own site.
Back in my day, if you had Helvetica installed on Windows, it wasn’t made for screen rendering and looked terrible. I remember putting Windows-friendly fonts higher in the stack for that reason
IIRC, most Helvetica fonts on Windows computers were installed by Adobe applications, which might explain why the fonts were designed for print instead of screen rendering.
The one in article is
The one it actually uses is It looks like a minor difference, but the former one has segoe ui before helvetica (which is hard-coded as Arial alias on Windows), so it would use segoe ui on Windows; while the latter (currently using) one would show the content as Arial on Windows.