They are different - Bound cuts out the density outside of the bound which is improper - Truncate Normal actually apply the cdf to the value outside of the bound: https://github.com/pymc-devs/pymc3/blob/master/pymc3/distributions/continuous.py#L736
They are different - Bound cuts out the density outside of the bound which is improper - Truncate Normal actually apply the cdf to the value outside of the bound: https://github.com/pymc-devs/pymc3/blob/master/pymc3/distributions/continuous.py#L736