I don't think the line is that bright. AFAIK there are quite a few areas in which the EU is more centralized than the USA. The relationship between US states and the federal government does explain certain differences to the EU, sure. But not if you simplify it to "US states are like souvereign countries" because so are EU members. EU and USA cannot be different because of something they have in common.
> This is also why the US Federal government can't just "pass a law" to do things
In a way, it can do that by changing the constitution. That requires the consent of a majority of states, but this is common in federations. The EU cannot change its "constitution" at all except with the consensus of all members.
> This is also why the US Federal government can't just "pass a law" to do things
In a way, it can do that by changing the constitution. That requires the consent of a majority of states, but this is common in federations. The EU cannot change its "constitution" at all except with the consensus of all members.