Degree of comparison

the degree of comparison of an adjective or adverb that describes the relational value of one thing with something in another clause of a sentence. An adjective may simply describe a quality, (the positive); it may compare the quality with that of another of its kind (comparative degree); and it may compare the quality with many or all others (superlative degree). ^[1] In other languages it may describe a very large degree of a particular quality (in Semitic linguistics, called an elative).
The degree of comparison may be expressed morphologically, or syntactically. In English, for example, most monosyllabic and some disyllabic adjectives have morphological degrees of comparison: green (positive), greener (comparative), greenest (superlative); pretty, prettier, prettiest; while most polysyllabic adjectives use syntax: complex, more complex, most complex.

1. The positive degree is the most basic form of the adjective, positive because it does not relate to any superior or inferior qualities of other things in speech.
2. The comparative degree denotes a greater amount of a quality relative to something else. The phrase “Anna is taller than her father” means that Anna's degree of tallness is greater than her father's degree of tallness.
3. The superlative degree denotes the most, the largest, etc., by which it differs from other things.

Change the degree of comparison without changing the meaning.
1.    Malacca is the oldest town in Malaysia.
2.    Peter is cleverer than any other boy in the class.
3.    Jupiter is the biggest of all planets.
4.    Very few boys are as industrious as John.
5.    India is the largest democracy in the world.
6.    Shakespeare was greater than any other playwright.
7.    Asoka was one of the greatest Indian kings.
8.    Greenland is the largest island in the world.
9.    Lead is heavier than any other metal.
10.    Very few animals are as useful as the cow.

Answers
1.    No other town in Malaysia is as old as Malacca. (Positive)
Malacca is older than any other town in Malaysia. (Comparative)
2.    No other boy in the class is as clever as Peter. (Positive)
Peter is the cleverest boy in the class. (Superlative)
3.    Jupiter is bigger than any other planet. (Comparative)
No other planet is as big as Jupiter. (Positive)
4.    John is more industrious than most other boys. (Comparative)
John is one of the most industrious boys. (Superlative)
5.    India is larger than any other democracy in the world. (Comparative)
No other democracy in the world is as large as India. (Positive)
6.    No other playwright is as great as Shakespeare. (Positive)
Shakespeare is the greatest of all playwrights. (Superlative)
7.    Very few Indian kings were as great as Asoka. (Positive)
Asoka was greater than most other Indian kings. (Comparative)
8.    No other island in the world is as large as Greenland. (Positive)
Greenland is larger than any other island in the world. (Comparative)
9.    No other metal is as heavy as lead. (Positive)
Lead is the heaviest of all metals. (Superlative)
10.    The cow is more useful than most other animals. (Comparative)
The cow is one of the most useful animals. (Superlative)


Source:
http://en.wikipedia.org/wiki/Degree_of_comparison
http://www.englishpractice.com/grammar/change-degrees-comparison/