Our paper on contrasting quantum decoherence and classical noise model is published in J. Chem. Phys. Quantum decoherence can be understood in several pictures. The most rigorous one being the system-bath model. In it, the bath is treated quantum mechanically and decoherence arises due to the system-bath entanglement generated by their interaction. A much simpler picture is the classical noise model whereby the effects of bath is to introduce a time-dependent stochastic term into the system. As such, decoherence appears from a statistical average of the stochastic but unitary dynamics. The intriguing question is whether the simple intuitive classical noise picture can reproduce the decoherence dynamics in a full quantum model. In this paper, we develop general criteria for the classical model to mimic quantum decoherence.