The difference is in the immutability and the way the list is declared.

const list = [1, 2, 3] declares a constant list, that is a compile-time constant, meaning its value is determined at compile time and cannot be changed at runtime.

var list = const[1, 2, 3] declares a variable that holds a constant list, but the value of that variable can be changed to a different list later in your code.

void main() {
  const list1 =[1,2,3];
  var list2 = const[1,2,3];
  
  list1.add(4); // <--error
  list2.add(4); // <--error
  list1 = [5]; // <--error
  list2 = [5];
  list2.add(6);
  print(list2);
}