They're nearly an identical format and both consist of teams that compete from all over Europe in a round robin group stage and then a knockout phase. The difference is that the Champions League consists of the top clubs in the world, those who finish at the top of the best leagues e.g. Bayern Munich or Real Madrid. The Europa League consists of teams that finish just below those teams in their leagues or are from smaller leagues e.g. Everton or Steua Bucharest.

Is that explanation sufficient?

champions league is all the best teams from around europe. europa league is all the semi good teams from europe. example

top 4 in premier league get champions league

5, 6 and sometimes 7th get europa league, and i think its some thing similar in spain and germany. other countries only get one or two.

UEFA Champions league is better and has better teams and its basically superior.