It has been explained to me, albeit, in layman's terms, that one of the reasons our modern cryptography works so well on classical computers is that they rely on prime factorization which classical computers don't do so well. This has been key to maintaining our computers and networks secured. One of the things Quantum computers do better than classical computers is prime factorization. How will the advent of Quantum computing impact cryptography? Will technologies like blockchains and bitcoin be affected?
AFAIK "classical computers" are optimized for multi tasking, user interface -- areas other than pure high speed number crunching. For these reasons an intel or AMD desktop CPU will emphasize integer (whole number) operations.
GPUs, ASICs and supercomputers are the opposite. Optimized for high speed FLOP (non integer, floating point, fraction/decimal) calculation.
Quantum computers are essentially identical to "classical computers". The main difference is modern day computers operating on binary registers capable of representing only 0 and 1. While a quantum computer in theory is able to represent a far higher number of values to give it a greater bit density per register. Quantum computers might also have a higher clock speed. The only thing missing with quantum computers is a working prototype or proof of concept which proves the technology is viable and superior to existing tech in performance and cost effectiveness.