2 questions about CompareTo() method in C#

I have 2 questions about the CompareTo() method in c#:

1. I read this method compares between the letters in two strings and returns the difference between the Unicode values of the first pair of letters, that aren't the same in the both strings. But when I run it, it always returns -1, 0, or 1. For example:

string s1, s2;s1 = "AARZNML";s2 = "AARZK";Console.WriteLine(s1.CompareTo(s2));

In the book it was said that the code must return -24, but it returns -1, when I run it.

2. What is CompareTo() method supposed to return when I compare a string with uppercase letters and a string with lowercase lowercase. For example I ran this code:

string s1, s2;s1 = "A";s2 = "a";Console.WriteLine(s1.CompareTo(s2));

and it returned 1, how can it be? Because 'A' is before 'a' in ASCII Table.