Question: what is the difference between hard x-ray and soft x-ray?
Answer: X-rays with high photon energies (above 5–10 keV, below 0.2–0.1 nm wavelength) are called hard X-rays, while those with lower energy (and longer wavelength) are called soft X-rays. ... The term X-ray is metonymically used to refer to a radiographic image produced using this method, in addition to the method itself.