Huge differences. Way too many to list. The main difference is that Windows
2000 - and the NT kernel that it is based on - doesn't have a DOS-like
("real mode") underbelly.

Bottom-line in practice: Windows NT (of which Windows 2000 is Version 5.0)
was built primarily for stability and security, and in its early days had
essentially no hardware/software compatibility support outside of a narrow
range of hardare and software. By Windows 2000, this hardware and software
support has been expanded very significantly while still retaining (and
strengthening) the security and stability basics. On the other hand, Windows
95 was created primarily for compatibility - to let people move from DOS and
Windows 3.x to a 32-bit operating system using the widest possible range of
legacy hardware and software. Accordingly, compromises had to be made, and
Win95 paid for these by foregoing any pretense of security, and taking a few
hits on stability.

There are many differences -- too many to cover in a simple newgroup
message.

A fundamental difference is the foundation. Windows 95 was based on
MS-DOS because Microsoft wanted Windows to be able to run DOS
programs. However, Microsoft also wanted to develop an operating
system that would be free of some assumptions made in DOS, so they
began parallel development of a distinct operating system. This other
system was first named Windows NT (for new technology), then Windows
2000, and most recently Windows XP.

Windows XP requires a bigger faster computer than Windows 95.

Windows XP formats the harddisk differently than did Windows 95.

Over the last ten years, viruses have become much more prevalent and
Microsoft has learned more about how to protect its software against
other people's mistakes, so Windows XP has more built-in protections
against defective software or invasive software than did Windows 95.

Bill Starbuck (MVP)