The SC has much in common with the top-of-the-line Theta S. So much so, it's easier for me to tell you what's missing and then you can go check out. According to a company representative I spoke with, Ricoh basically dropped two features for the SC, based on consumer research. First, the SC has a continuous recording time of 5 minutes, compared to 25 minutes with the Theta S.
Second, Ricoh removed the Micro-HDMI port for the SC, and with it the camera's ability to live stream. Frankly, though nice to have, using the Theta S for live streaming is sort of a pain. It's understandable that feature got the ax in exchange for a lower price.
One more minor difference: Instead of the soft-touch exterior of the Theta S, the SC is resin. It still comes in multiple colors, though: white, beige, blue and pink.
Ricoh updated its Theta S iOS and Android apps for controlling the camera, too, mainly making the interface more intuitive for less tech-savvy users. (I mean, look how happy those people in the picture are to be using it!)
The Ricoh Theta SC is available in the US now for $300. UK and Australian details weren't available, but that's approximately AU$400 or £250.