Telemetry monitoring is a type of cardiac monitoring. Only difference is that a small transmitting device is attached to the person which transmits to the receiver elsewhere. This allows the person to move as well as be away from the main machine, within a given transmitting range of the device.
Telemetry has a wider meaning as well: to measure at a distance. It is also the term used for measured data from satellites and spacecrafts being transmitted to the earth.