The precise differences naturally depend on the individual state, but in general, state constitutions tend to be much longer and more detailed. Where as the US Constitution provides a general framework and includes specifics only where necessary, state constitutions tend to enshrine A lot of detailed law that you might expect to find in a statute.
They both have similar importance, but on a different scale. Obviously the US Constitution is superior to other facets of federal law, and also superior to the Constitutions and laws of the states. State constitutions take precedence over state statutes and other aspects of a state law framework, mirroring the relationship of the federal Constitution to federal law, while being a subordinate to it.
