Jarret W. Buse has written a few posts explaining and summarising the differences of some older and newer file systems available for Linux: BTRFS, Reiser and JFS.
The B-Tree File System was created by Oracle in 2007. The file system was added to Linux Kernel 2.6.29 in 2009. The maximum number of files is 8,446,744,073,709,551,616 or 2 to the 64 power of files. The maximum file length is 255 characters. The theoretical max file size limit is 16 EB, or 8EB because of a kernel limitation in Linux.
The Reiser File System (Reiser3) was created by Namesys in 2001 and added to the Linux Kernel in version 2.4.1. Reiser3 was the first Journaling file system included in the Linux Kernel. Reiser4 was introduced in 2004 which was an improved Reiser3 file system.
Journaled File System
The JFS file system is a 64-bit file system created by IBM and ported to Linux in 1999. A stable version was released in 2001. The first implementation was the Linux Kernel 2.4.18. JFS was originally released in 1990 with AIX version 3.1. It is sometimes referred to as JFS1.
Click on the links above for the full introduction into these file systems.