Yea, explorer is userland although I would suspect NT's explorer wouldn't run on win98. Haven't tried, but I'd at least expect it to depend on some NT specific things.
The version strings in about dialog, however, are generated by the system. So, even NT executables will give win98 version info in about box when you're running them on win98. You can take software from old versions of windows and the about dialog will claim the version matches the system version...