A little history, back when RISC was the up and coming thing, SUN wanted one, but no one had one for sale. So they made one up. Originally known as Sun Processor ARChitecture, it was not actually a chip per se, but a specification (SUN not owning fabrication plants). Several chip manufacturers, notably Texas Instruments and Cypress (later Ross Technologies) actually produced the chips.

Bill Joy from Sun and Dave Patterson from Berkely started work on the SPARC architecture in 1984. In 1986 they produced they the version 7 spec (32 bits) which was then made into the first line of SUN workstations, the SUN 4/xx0 line of workstations.

The line has been updated several times over the last 18 years. SuperSPARC and SuperSPARC-II is a superscalar version of the original 32 bit CPU. Ross produced the hyperSPARC which had a faster clock (200Mhz vs. 85Mhz in the SuperSPARC). Also the microSPARC was produced (being a cheaper, less powerful cpu similar to Pentium vs. Celeron or Athlon vs. Duron)

Finally there are the 64 bit versions. SPARC64 produced by Fujitsu (who actuall owned Ross for awhile) focused on out of order execution as opposed to Sun's chosen one, the UltraSPARC. The UltraSPARC did not do out of order execution arguing that memory latency would negate the benefit. What it did add though was a set of graphics operations (like MMX or HP's MAX on their PA-RISC).