This compares every item in the list to every item in the other list. This won't work if both have letters (e.g. TK132C and TK132P wouldn't match). If that is a problem, comment below.
list_1 = ['TK123','TK221','TK132']
list_2 = ['TK123A','TK1124B','TK221L','TK132P']
ans = []
for itm1 in list_1:
for itm2 in list_2:
if itm1 in itm2:
break
if itm2 in itm1:
break
else:
ans.append(itm1)
for itm2 in list_2:
for itm1 in list_1:
if itm1 in itm2:
break
if itm2 in itm1:
break
else:
ans.append(itm2)
print ans
>>> ['TK1124B']