"Gamma rays are almost produced alongside alpha and beta" 
Do you mean "always produced"?
 yes thanks I'll change it
It might be useful to mention that Gamma-rays are generally associated with nuclear transitions, while X-rays are generated by electronic transitions.  Gamma-rays are usually more energetic than X-rays, but this is not always the case.  For example the 14.4 keV gamma-ray from Co-57 -> Fe-57, is less energetic than many X-rays.
Also, gamma rays can be formed by matter/antimatter interactions, such as electron-positron annihilation.
 
All Wikipedia text 
is available under the 
terms of the GNU Free Documentation License