The difference between European football and NBA can be seen as the difference between European basketball and NBA. For example, European basketball, different countries have different leagues, and Europe has a cup. The same is true of European football. Each country has its own football league, and the better clubs in each country represent their respective leagues in the Champions League and the European Union.
European football is in a leading position in the field of football, and NBA is in a leading position in the field of basketball. The difference between the two is that NBA is a national league and European football is the floorboard of the whole European football.