There are improvements in Solaris 2.x.
1) OpenWindows 3.3+ (in Solaris 2.3+). Includes X11R5 and Display PostScript. X11R6 in Solaris 2.6, X11R6.4 from Solaris 7 HW 11/99 onward.
2) Motif & CDE.
3) ANSI-C and POSIX development environment.
4) POSIX threads (2.5)
5) POSIX and X/OPEN command environment
6) UNIX 95 conformance.
7) UNIX 98 conformance (Solaris 7)
8) Posix shared memory and semaphores (2.6)
9) Multi-threaded kernel and real threads.
10) Real-time feature in the kernel
11) Faster clock ticks (optionally 1000Hz in 2.6)
12) Large files (2.6)
13) True multi-processing.
14) Goodies: vold, admintool and Wabi.
15) Easy patch installation/administration through installpatch/patchadd.
16) All software in easy to manage "packages".
17) Power management software & suspend/resume
18) Access control lists
19) NFS Version 3 and NFS over TCP (Solaris 2.5+).
20) A better automounter, autofs (not more /tmp_mnt and symlinks).
21) Jumpstart/autoinstall - hand off installation of clients.
22) Much better MP support.
23) Faster networking (ATM, fastethernet).
24) 64 bit OS (Solaris 7)
25) IPv6 (Solaris 8)
26) IPsec (Solaris 8)
27) Kerberos 5 client support (Solaris 8)