Things that changed here in Germany (which I can think of off the top of my head):

• No presidential role. We don’t have a single person with that much power anymore. The most powerful is the chancellor now.
• No emergency laws. Many nations have laws that when something goes wrong, their president gets superpowers to do whatever they want. This is regularly abused, not just by Hitler. To my knowledge, we don’t currently have any such law.
• Secret voting. It is now illegal to make it public who you voted for. When Hitler rose to power, Nazis would sit in voting places and pressure people to vote for Hitler. And they would heckle people who didn’t want to show their ballot card.

Having said all that, it should also be said that we do still currently have a very real Nazi problem. It’s a few steps in the right direction, but no silver bullet.