The difference between Quantum bit and Qubit

Quantum bit as a noun (physics):

A normalized linear combination of an "up" state and a "down" state for, say, the spin of an electron. (The "up" and "down" states can be "measured" along some particular direction. Such measurement could be performed by applying a magnetic field in that direction, in which case the electron responds non-classically in either one of two ways: (1) it emits no photon, in which case it would have been in the "up" state, or (2) it emits a photon of a certain energy (always the same), in which case it would have been collapsed in the "down" state. Afterwards, the "north" pole of the electron's magnetic moment points towards the "south" pole of the magnetic field; so it would stay in the "up" state, regardless of which direction it collapsed in. Pre-measurement, the coefficient of the "up" state times its complex conjugate gives the probability of collapsing in the "up" state (during measurement) and the coefficient of the "down" state times its complex conjugate gives the probability of collapsing in the "down" state (during measurement). The two probabilities add up to one, i.e., the linear combination is normalized.)

Qubit as a noun (computing):

A quantum bit; the unit of quantum information described by a superposition of two states; a quantum bit in a quantum computer capable of being in a state of superposition.