As adjectives the difference between cosy and friendly
is that
cosy is affording comfort and warmth; snug; social while
friendly is generally warm, approachable and easy to relate with in character.
As nouns the difference between cosy and friendly
is that
cosy is a padded or knit covering put on an item to keep it warm, especially a teapot or egg while
friendly is (sports) a game which is of no consequence in terms of ranking, betting etc.
As a verb cosy
is to become snug and comfortable.
As an adverb friendly is
in a friendly manner, like a friend.