As verbs the difference between express and behave
is that
express is (
senseid) to convey or communicate; to make known or explicit while
behave is (
label) to conduct (oneself) well, or in a given way.
As an adjective express
is (not comparable) moving or operating quickly, as a train not making local stops.
As a noun express
is a mode of transportation, often a train, that travels quickly or directly or
express can be (obsolete) the action of conveying some idea using words or actions; communication, expression.