If Chelsea succeed in winning the conference league they will be European champions and if Manchester United fail to win the Europa league then Chelsea will be said to have a better season than United. At the time both sides are struggling to win games and stay consistent however Chelsea are still better than United because of their standing in the league table and until United win the Europa League title Chelsea are better than them.
it is more confident to say Chelsea can win the Conference league than saying Manchester United are going to win the Europa league, and this is very evident in the strengths of the different leagues in which both teams are participating respectively. For Chelsea they are not really doing that bad as Manchester United both in the EPL and in their respective European competitions. Chelsea is having a complete domination of their competition meanwhile Manchester United struggles and their opponents are mainly of equal strength which means they could be knocked out at any stage if they don't maintain a high level of form when they return from the international break.