The World Cup is the most difficult to win in sports.
The World Cup is much difficult to win because it is only played in four years and also Tho teams(England,Ghana, Germany and the rest) don’t get time to train like they do in their clubs(training is only done when there’s going to be the tournament that is the World Cup). It’s difficult to adapt to a different team when you aren’t completely sure what your teammates are going to be doing on the field.
Mostly they’re always new selections so it’s sometimes difficult to cope till you play your first match especially.
Both champions league and World Cup have different level of competition. I will go in for fifa World Cup because champions league is quite easy to predict with the some one or two teams that will win the tournament.