I have them both, and a third one too. There are no difference. If you have adequate experience, it makes no difference what logo your ticket has on it.
The weak points with the FAA system is the published test answers, and that you can be completely lost in a subject, since you only need 80% pass in all the subjects combined.
In the JAA system you need a minimum passing score in each subject, to ensure a basic knowledge in every subject. The weak point in Scandinavia is the lack of competent personnel at the license offices - most have no clue (and no operational experience, apart from recreational Cessna flying at best) and are therefore reluctant to apply common sense, thus they stick to the books - the books they donīt understand.
E.g. I asked why my test included questions about Omega.....history at the time. I could actually fail in navigation if I answered wrong about Omega, despite Omega being long gone. When I tried to ask about this, they had no clue and only pointed to the books. However, I think the curriculum has been updated since.
In any case, there should be an easier way to convert for those with adequate experience, say 3-4000 hours multi crew experience from larger jets.
Remember, the first in space was a dog - its not that hard! Lets keep it simple!