Epic is an extended long narrative poem in elevated and dignified language celebration the feats of a deity or demigod or other legendary heroes. It has a colloquial meaning of extending beyond the usual or ordinary method.
"An epic is a long narrative poem."
Epoch is a unique period of history especially one considered remarkable and noteworthy. It is the time used as reference point to an event or occurrence of the past.
Epic is used most often these days as an adjective that means impressive or remarkable.
“That party last night was epic.”
Epoch is a noun meaning a period of time in a person’s life or in history. It is a synonym for ‘era’.
“The break-up of the Soviet Union began a new epoch in European history.”