Comparing more and less
Italian adds no ending to the adjective (tall → taller). Instead più (more) or meno (less) goes in front of it, and than becomes di or che. The adjective agrees with its noun as usual: più alta for a woman.
Marco è più alto di Luca.
Marco is taller than Luca.
Questo libro è più interessante di quello.
This book is more interesting than that one.
Oggi è meno freddo di ieri.
Today is less cold than yesterday.
Than: di or che?
English uses than for everything. Italian has two words, and the choice depends on what you are comparing.
di and che
di
di is used when two different people or things are compared: before a noun, a pronoun or a number.
Sono più veloce di lui.
I am faster than him.
Ho più libri di te.
I have more books than you.
Ci sono più di venti persone.
There are more than twenty people.
che
che is used when two things of the same kind are set against each other: two adjectives, two nouns as amounts, or two places.
È più simpatico che bello.
He is more likeable than good-looking.
Ho più amici che nemici.
I have more friends than enemies.
Fa più caldo in Italia che in Germania.
It is hotter in Italy than in Germany.
As ... as
For as ... as with an adjective, use come. The così in front is possible but not needed.
Marco è alto come Luca.
Marco is as tall as Luca.
Lei è così intelligente come lui.
She is as intelligent as him.
For as much / as many ... as, use tanto ... quanto. Before a noun, tanto agrees with it: tanto tempo, tanta pazienza, tanti amici, tante idee. With a verb it stays unchanged.
Ho tanto tempo quanto te.
I have as much time as you.
Lui mangia tanto quanto me.
He eats as much as I do.
