Gamma radiation, also known as gamma rays or hyphenated as gamma-rays is electromagnetic radiation of high frequency and therefore high energy.
Gamma rays from radioactive decay are defined as gamma rays no matter what their energy, so that there is no lower limit to gamma energy derived from radioactive decay.
Gamma rays have characteristics identical to X-rays of the same frequency—they differ only in source.
Gamma rays : distinguished by their origin emitted by neucleus. nnX-ray : emitted by definition by electrons outside the nucleus.