From the PRS website's FAQ: (
http://www.prsguitars.com/csc/faq_s2.html)
"3. How is my Starla different from a Starla S2?
The S2 Series was designed for a new audience. The instruments in the S2 Series have all the tone and playability that our Core guitars feature. The guitars and options have been streamlined, in part by simplifying the body carve, standardizing the neck scale length and shape, utilizing a new finish process, and using a mix of Core and new hardware.
Body Carve: The original Starla featured a more complicated, violin–style carved top. The S2 Starla features a more streamlined, beveled carve.
Scale Length and Neck Shape: The original Starla has a 24.5" scale length Pattern neck. At this point, all of the guitars in the S2 Series (including the Starla) incorporate a 25" scale length Pattern Regular neck to streamline the manufacturing process.
Finish: The S2 Starla, along with the entire S2 Series, incorporates a new finish system where the color coat is embedded under a polyester basecoat and completed with an ultra–thin layer of acrylic urethane topcoat.
Bridge: Both the Starla and S2 Starla use a Tune–o–matic bridge. The tailpiece on the original Starla is a Bigsby B5, and the tailpiece on the S2 Starla is a Bigsby B50.
Tuners: The original Starla features Vintage–style tuners. The S2 Starla, along with the entire S2 Series, feature S2 locking tuners.
Pickguard Assembly: The electronics control layout is identical to the layout on the original Starla (volume, push/pull tone, 3–way blade switch). The pickups and specific switches have been sourced to very closely replicate those offered on our Core line. The pickups and electronics are mounted to an integrated pickguard assembly."