Maxvorstadt: Yep, NT was a Win 98 vlone, with slghtly better networking abillities (Hm, not sure if I wrote abillities right!).
NT = Neandertal Technology :-D
As jamyskis said above, Windows NT and 9x are completely different product lines. IBM and Microsoft collaborated circa the late 80s to create a next-gen 32bit operating system which became OS2. It was designed by Dave Cutler of VMS fame. After a few incarnations of OS2, Microsoft no longer wanted to collaborate with IBM on the project any more so it split in two (around OS2 1.3 if memory serves correctly), and IBM continued to develop and market the product as OS2 throughout the 90s, while Microsoft took the codebase and forked it into Windows NT.
Windows 95 on the other hand, was a graphical shell on top of MSDOS just like Windows 3.1 and earlier versions of Windows were, the main difference being that Win95 had the GUI bundled and integrated with the underlying DOS operating system. Windows 98 and ME were the latter incarnations of the MSDOS based versions of Windows. All of these are essentially the MSDOS operating system under the hood and are completely unrelated to the Windows NT product in every way.
The NT family of operating systems that spawned from OS2 became Microsoft's high-end enterprise product line, being a proper 32bit OS from the ground up with no ancestry in MSDOS. This continued from the early to late 90s under the product label Windows NT, ending with the NT 4 series product, then continued as Windows 2000 (NT5) -> Windows 2003 Server -> Windows 2008, etc. on the enterprise line.
Windows XP became the first Microsoft operating system designed for the consumer market which was based on the NT kernel and can be seen as a fork or branch of the NT lineage between Windows 2000 and 2003. So under the hood, XP and its predecessors Windows Vista, Windows 7, Windows 8.x, and Windows 10 all can trace their history back to Windows NT and before that to OS2.
The only real overlap the NT family tree of Windows products has with the 90s era DOS based hack Windows products have are some amount of API compatibility to a limited degree, and from Windows NT 4 onward Microsoft borrowed the user interface design it used in its consumer operating system line (the DOS based ones) for the NT series, although the GUI lacked features compared to the consumer OS at any given time up until XP was released when it became the "head branch" of Microsoft's UI development essentially.
Other than the visual similarity of Microsoft switching the NT user interface design from the Windows 3.x styled user interface that NT 3.51 and earlier versions of NT used, to the Windows 9x styled user interface that NT4 and later products in the family had, calling NT a clone of Windows 98 is quite inaccurate on pretty much every possible level. :o)
The easiest way for anyone unfamiliar with the lineage of these products to figure it out though was to try to install and run software designed for one of them on the other. More often than not, the end result was a tragic miserable failure due to the immense incompatibilities and differences between the product lines, especially when it came to video games. :oP