LIKE - AS

LIKE - AS : When are they used?

• Like
  
  Like is a preposition, used before a noun or pronoun, to say that two things are similar.
  They behave or operate in the same way.
  
  
  • In his job he works like a slave.
  • The children swim like fish.
  • The boy runs like a hare.
• As
  
  As, as a preposition, before a noun or pronoun, is used to refer to jobs or functions,
  the role of a person or the use of something.
  
  
  • My father worked as an accountant.
  • Caroline was employed as a teacher.
  • The author is respected as a writer.
  • He used a saucer as an ashtray.

• Compare
  
  
  • I am your friend, and as your friend I advise you to be careful.
    = It is my role as a friend to warn you.
  • I don't know you, but like your friend, I advise you to be careful.
    = I think the same way as your friend. I am like your friend in that respect.

LIKE and AS are also used as below:

LIKE
As a verb meaning ‘enjoy’	• Sam likes chocolate. / Children like milk. • I like going to the beach. / She likes getting up early.
As a noun : the ‘like’ (=similar types)	• I enjoy classical music but I prefer jazz, rock and the like. • You’re not going to associate with the likes of him!
As an adjective meaning ‘similar’	• They’re as like as two peas in a pod. (= as similar as) • The two experts were of like mind. (= of similar mind) • We responded in like manner. (=in a similar way)
In spoken English, ‘like’ can be used as a conjunction connecting two clauses. *NB: Considered incorrect in traditional grammar books, so avoid in academic writing.	• He acted like he owned the place. (= as if) • Nobody can sing like you do. (= the same way as) • Like I said, you’re welcome to join us for lunch. (=as I said)
AS
As an adverb - ‘just like’	• She was extremely polite, as always. • The ‘h’ in ‘heir’ is silent, as in ‘hour’
As a conjunction -connection two clauses - meaning ‘while’ - meaning ‘although’ - meaning ‘the way in which’ - meaning ‘because’ or ‘since’*   (*use carefully to avoid any confusion)	• It's very expensive, as you know. • He won the election, as was expected. • The phone rang as I was watching television. (=while) • Tired as he was he still finished the race.(although) • We left the room as it was. (the way in which) • Julie may need help as she’s new to the job. (=because)