This is true - the difference lies in where they come from and how fast they're going. Heat a metal wire in a vacuum.
Electrons gain enough energy to leave the wire and form a cloud around it.
These electrons can be attracted by a sheet of metal carrying a positive charge. They move towards it, gaining speed as they go. This is what happens in a television. In this case the electrons will reach about one tenth of the speed of light. A typical beta-particle , however, leaves a nucleus with an energy equivalent to being accelerated through 1 million volts.