ps -aux is the proper old ps. All true unixes use ps -aux. It's true POSIX and UNIX standard, documented by ANSI, ISO, IEEE and Open Group. At some point SCO and Solaris insisted on changing it to ps -ef with obligatory "-". The main difference is that where all "aux" unixes provided compatibility for admins coming from "broken" standard and added "ef" as a switch to achieve the same output, Solaris remained "ef" only. It is important to remember, however, that you will find ps -aux in SunOS as late as revision 4. Changing it to -ef was something done on purpose, to break standard and establish licensed System V (or system 5). At that point SunOS's standardized scsi devices like /dev/sd0a turned into /dev/dsk/c0t3d0s0 behemoths, fstab became vfstab, nfs exports file was turned into /etc/dfs/dfstab and killall command started killing literally all, forcing machine to die, instead of stopping a bunch of processes of the name specified after command (now, just how stupid is that).
Basically, what I'm trying to point out is that Solaris wasn't always like that - SunOS was once pretty much like any other Unix out there, however, Solaris was MADE into the weirdo we all know, and the sole purpose of the transition was to make it weird and break standards.