Envelope Vs RMS

The RMs detector converts the thermoelectric effects of the RF signal into a voltage. Basically output voltage would correspond to the temperature as the matched load heats up. The envelope detector tracks the envelope of the modulated RF signal. Usually, the envelope detector has a larger bandwidth, a wider frequency range, and a higher dynamic range. On the other hand, accuracy and temperature stability are important for RMS detectors. if you known modulation type there is a clear relation between peak power (max. value of envelope power values) and RMS power. 

Thansks for information.

If I would like to calibration RF modulation type power,whcih one is more suitable? 

If I would like to calibration RF CW type power,whcih one is more suitable? 

Usually the envelope detectors are not suitable for calibration. These detectors are used for different tasks such as protection of Power Amplifiers or receiver inputs. Or as a demodulator for pulse-modulated signals. For calibration I recommend you take RMS detector - there are generally 2 types: log detectors and true power detectors