There are three types of comparative forms in Italian:

 

- The comparative of superiority which is formed by adding the adverb più (more) before the qualifying adjective:

 

Anna è più alta di Marco. (Anna is taller than Marco.)

 

- The comparative of inferiority which is formed by adding the adverb meno (less) before the qualifying adjective:

 

Marco è meno alto di Anna. (Marco is less tall than Anna.)

 

- The comparative of equality which is used to compare two or more qualities possessed by both terms of comparisons. The second term of comparison is introduced by the adverbs quanto or come (as … as ):

 

Mariangela è alta quanto Anna. (Mariangela is as tall as Anna.)

 

The second term of comparison is introduced by the preposition di or the conjunction che.

 

There is no fixed rule as to when choose di and when prefer che.

 

Generally you use di before a noun / pronoun not introduced by a preposition, or before and adverb:

 

- Anna è più gentile di Marco. (Anna is nicer (kinder) than Marco.)

- Di solito Anna è meno gentile di te. (Usually Anna is less nice (kind) than you.)

- Oggi sono più tranquillo di ieri. (Today I feel calmer than yesterday.)

 

Generally you use che before a noun / pronoun introduced by a preposition, an adjective, a participle, or an infinitive verb:

 

- Anna è più gentile con Marco che con me. (Anna is nicer (kinder) to Marco than to me.)

- Marco preferisce mangiare che parlare. (Marco prefers to eat rather than talk.)

- Anna è più simpatica che intelligente. (Anna is nicer than smarter.)