What is the difference between List.of and Arrays.asList?

Java 9 introduced new factory methods for lists, List.of:

List<String> strings = List.of("first", "second");

What’s the difference between the previous and the new option? That is, what’s the difference between this:

Arrays.asList(1, 2, 3);

and this:

List.of(1, 2, 3);