RV
Вот как накидал я, можете оттолкнуться от этого:
import difflib
t1 = 'Hello, Slava!'; print('Input 1:', t1)
t2 = 'UnHello, Slovo.'; print('Input 2:', t2)
differ = difflib.Differ()
diff_obj = differ.compare(t1, t2)
diff_text = ''.join(diff_obj)
diff_list = [diff_text[i*3:(i+1)*3] for i in range(len(diff_text)//3)]
print('All comparisons:', diff_list)
result = [x for x in diff_list if x[0] in "+-?"]
print('Only difference:', result)