Nitpick: the C in TCXO stands for "Compensated", not for "Controlled", like in OCXO.
That means that the resonator of an OCXO is held at a constant temperature, while that of a TCXO is at the ambient temperature, but the temperature is monitored and a compensation circuit adjusts the resonance frequency, maintaining it as constant as possible.
That means that the resonator of an OCXO is held at a constant temperature, while that of a TCXO is at the ambient temperature, but the temperature is monitored and a compensation circuit adjusts the resonance frequency, maintaining it as constant as possible.