The configuration of a robot system is a complete specification of the position of every point of that system.
The configuration space or C-space is the space of all possible configurations.
Thus, a configuration is just a point in configuration space.
denotes a configuration, whereas denotes configuration space
the number of degrees of freedom of a robot system is the dimension of the configuration space.
Robots move in a 2 or 3-dimensional space represented by or respectively. This may also be referred to as the workspace. On a robot arm, this would be the space reachable by the end-effector.