Quantum computing is unique in that it uses quantum mechanics in order to function. A normal computer operates in '1s' and '0s', and appear in lines of code, such as 10011001. Quantum computing uses quantum bits, otherwise known as 'qubits.' A qubit uses superposition, which allows it to exist in more than one state at once. This essentially means that a qubit is both a '1' and a '0' at the same time, allowing for more powerful computers because more information can be stored.
Quantum computers are better than even the fastest supercomputers due to their computing abilites. A supercomputer could sort hundreds of strands of DNA quickly, but couldn't find smaller subtlties in the DNA, let alone have enough space to store the knowledge it could potentially find. A supercomputer would try to use brute force to solve equations, but a quantum computer would look for patterns and solve it in an easier way. A quantum computer can also store more information, especially with the use of qubits. However, quantum computers require more heavy hardware, such as superfluids to keep quanutm processors cold, superconductors to allow electrons to flow through them without resistance, superposition, which is what the qubits are. They also entaglement that allows to qubits to be interconnected with each other, allowing changes on one qubit to directly affect the qubit it is entangled with.