Here is one theory:

In 2/4, you probably love calling with A-4 offsuit UTG. 'cause its only $2.

In 10/20, you throw it away like you should.

2/4 seems like pennies to you after you play in $100+ pots at the 10/20 table, therefor your 2/4 starting hands probably deteriorate. Play the games correctly and you should win both.