Comparisons is a very large chapter in Grammar, we cannot analyze all the details in one post. I will try to explain the very basics with some examples.Ο Γιώργος είναι ψηλός = George is tall : We have no comparison here. The adjective tall indicates a quality that George has.Ο Γιώργος είναι ψηλότερος από τον Κώστα = George is taller than Kostas : Here we do have a comparison. The adjective "ψηλός" (tall) comes in a comparative degree (ending: - τερος (male) - τερη (female) - τερο (neutral)).Then we put the preposition “από” and the noun by which the comparison is made in accusative case (τον Κώστα).Similar examples:Ο Νίκος είναι μεγαλύτερος από τον Γιώργο = Nikos is older than GeorgeΗ Μαρία είναι μικρότερη από την Ελένη = Maria is smaller than HelenOne of the simplest ways not to change the adjective ending is to precede it with the word “πιο”.Examples:Ο Γιώργος είναι πιο ψηλός από τον Κώστα = George is taller than KostasΟ Νίκος είναι πιο μεγάλος από τον Γιώργο = Nikos is bigger than GeorgeΗ Μαρία είναι πιο μικρή από την Ελένη = Maria is smaller than HelenFor more information and details:http://users.sch.gr/ipap/Ellinikos%20Politismos/Yliko/Theoria%20Nea/epitheto-parathetika.htmhttp://users.sch.gr/parantoniou/site/glwssa/grammar_vathmoi_epithetwn.html
--------------------------------------------------------------------------------------------------------------------------- Vasiliki Baskou, Instructor/Director, https://learn-greek-online.com.