Pohnpei is exactly right. Enclose and shows are exact rhymes. Enclose and row are close rhymes known as near rhymes or slant rhymes. One thing people sometimes get confused about is that words have to be spelled the same to be exact rhymes such as "boat" and "coat". This is not the case rhyme is based on the sound not the spelling.
The rhyme scheme here is A-B-A-B-C-C. Look at the last words of each line:
Enclose and row do come close to rhyming, but they don't really so they are A and B.