The UEFA Champions League is the most prestigious club soccer competition in the world. It's the most popular and highest grossing, one which every footballer plying their trade in Europe will want to win at least once in their career.
The FIFA World Cup is the global soccer competition that is competed among nations of the world and is organised by world football governing body as it's topmost competition with lower age world cups held every two years.
The Champions League recoups a lot through its 8-month yearly calendar while the FIFA World Cup is held once in four years and for just a month, despite this schedule, the FIFA World is larger in numbers than the UEFA Champions League.
The highest grossing Champions League revenue for UEFA through media rights was in the 2018/19 season where UEFA made $2.37bn while in 2018, the FIFA World Cup in Russia grossed $5.37bn in revenues while making about $3.5bn in profit.