Quantum computers use a different kind of bit, namely "qubits". A qubit is not just 1 or 0, but both at the same time. Or rather: a qubit is 1 with a certain probability and 0 with a certain probability. We call this superposition and is the basis for quantum computers.
This difference, between qubits in superposition and bits, is one of the most important differences between normal and quantum computers. Qubit have a number of special features. In a computer it is clearly visible whether a bit has the value 0 or 1. You can't just see that in a quantum computer. To find out the value of a qubit, it must be measured. When a qubit is measured, it assumes a certain value.
Another characteristic of qubits is that they can become "entangels". Two entangled qubits depend on each other. If a qubit assumes a certain value, then the value of the other qubits can be predicted.
Because qubits do not have just one value and you can also entangle them with each other, you can theoretically use them faster than with a normal computer. With a normal computer with 8 bits you have 2ˆ8 = 256 bits of computing power. With a quantum computer with 8 qubits, this is theoretically 2ˆ (2ˆ8) = 1.2 * 10ˆ77 more computing power compared to a normal computer. That is countless more computational power. However, it is important to note that quantum computers cannot do all calculations faster than normal computers. What can they do?