Finding difference in two strings.

Question

I want to use LINQ to find the difference in two string

 

The first string is the correct Answer the second is a users Quiz what I need to know is what questions they answerd incorrectly the question number and there respose.

 

results expected "1x,2a,3b,10b,20b"

 

var Answer = "A,B,D,A,D,B,A,C,B,A,C,D,B,D,B,D,D,B,A,D,D,B,B,A,B,A,D,C,B,C,C,B,A,A,C,A,D,B,C,C,A,D,A,D,A,B,B,B,A,B";

var Quiz = "x,A,B,A,D,B,A,C,B,B,C,D,B,D,B,D,D,B,A,B,D,B,B,A,B,A,D,C,B,C,C,B,A,A,C,A,D,B,C,C,A,D,A,D,A,B,B,B,A,B";