Dart was initially built to be a newer and faster alternative to Java and PhP. So it can't really be anything but BETTER compared to those two.
Coding Syntax Difference between Java and Dart
Java and Dart don't differ that much when it comes to their syntax. But Dart tends to be focused more on having a shorter code. As you can see on this comparison below:
Dart Is a compiled language, thus it performs way better than Java and PhP.
It's also known that Google itself is using Dart internally within its own servers.
Dart is Cleaner and Faster Programming Language compared to Java.