Windows 95
At the current time Windows 95 comes in two major versions. The original Windows 95 released in 1995 and the OSR2 (OEM Service Release 2). The latter comes only preinstalled on some computer systems purchased after May 1997, it cannot be purchased as an upgrade or a software product. There exists also a Service Pack upgrade for the original Windows 95.
To identify the version of Windows 95 on your system, open the Control Panel and click on the System control applet. Select the General page of the resulting System Properties dialog and you will see a long version number below the words Microsoft Windows 95. The original release has the version number 4.00.950, and the OSR2 has the version number 4.00.95B. If you applied the Windows 95 Service Pack 1 to the original release, the version number shown will be 4.00.950a.
The major difference between the original release and OSR2 is FAT32. FAT32 is a 32-bit file system that avoids much of the wasted disk space inherent in the original 16-bit FAT, the file system used by DOS and the original Windows 95. FAT also cannot support hard disk larger than 2 GB, while FAT32 can handle such large disks with ease. On the other hand, no other operating system can access a disk that uses FAT32, not DOS, not Windows NT, and not even the original release of Windows 95. The full extend of the differences between the OSR2 and the original release of Windows 95 have not been determined, and you should use extra caution in applying tricks and tips developed for the original release of Windows 95.