My question is:

Will there be some problems if I develop application in Windows'98
environment, which will be actually used in Windows NT environment ?

I mean the .exe file is produced on my computer where I have Windows'98
installed, but that application is supposed to work on computer of my
custemer where he has Windows NT Workstation V4.0 installed ?

        Thanx in advance for any answer.

Some of the main differences are the directories.

Like on NT the system directory is WINNT\System32 instead of
Windows\system32

and on NT, you can make applications available to only one user so your
shorcuts may get insalled in the users start menu instead of all users start
menu

ie

C:\WINNT\Profiles\username\Start Menu\Programs
instead of
C:\WINNT\Profiles\All Users\Start Menu\Programs