What was the difference between green beret training now compared to vietnam?

The purpose of the Army Special Forces (the correct name for that unit) hasn't changed much, but it's about half the size it was back then. They've also become a lot more globally active, and have expanded their capabilities to include pretty much everything, which means the burden and responsibilities for each individual has increased. Since counter-insurgency has been the name of the game for the last few decades, they've also been the most active unit in USSOCOM pretty much ever since Somalia.

According to the training cadre at JFK, the mental aspects of the training has gotten a lot tougher since its original creation, and they've gotten more selective about choosing candidates, especially the officers.

Much more intense, as technology grows, so does the need for additional training.