The premier league is England's top division (Spain's is La Liga, Italy's is Serie A, etc). The Champions League is when the best teams from those different divisions around Europe play together to work out who the best team in Europe are.
The 'question' is whether Messi is as good as Maradona. Most people think Messi is the best player in the world right now (although some say it's Christiano Ronaldo, others say Wayne Rooney) but Maradona is recognised as one of the greatest players ever, alongside people like Pele, Best, Cruyff and
Zidane That's why it's the 'big' question.