import difflib

def matches(first_string,second_string):
    s = difflib.SequenceMatcher(None, first_string,second_string)
    match = [first_string[i:i+n] for i, j, n in s.get_matching_blocks() if n > 0]
    return match

first_string = "this is a sample string"
second_string = "this is also a sample string"
print matches(second_string, first_string )