Examples of difference between Hidden Markov Model and Bayesian Network?
A Hidden Markov Model can be expressed as an instance of a Bayesian network of a particular form.  Consequently, a HMM can be viewed as an special case or kind of Bayesian network.  Bayesian networks are more general, and can express other kinds of probabilistic structures as well.  All HMM's are Bayesian networks, but not all Bayesian networks are HMMs.