SBrick is a smart brick designed for gamers. You can connect motors and lights and control how they are used because all four of the connections on the SBrick are outputs.
SBrick Plus is different in that the four connections are both outputs and inputs. This means you can attach sensors to an SBrick Plus and it will monitor the device to which it is connected. This is a big step up because it allows you get into programming and robotics, and build models that actually react to the environment they’re in. For example, if you connect a light sensor to SBrick Plus, you can program your MOC to turn on headlights automatically when it gets dark; and that’s just one basic example.
The company likes to say that SBrick is for gaming, and SBrick Plus is for education, but actually, both are for both - it just depends on what you want to do.