Similar but not the same: As and Like.

"Like" and "as", they both are translated in Spanish using the same word ("como"). That´s why we get confused with these two words.
But in English they are quite different. In the practice the main difference is that while "like" is a preposition, "as" is a conjuction, so if after this article, the difference is still not clear I recommend:


1. See if what you need in your sentence is a preposition or a conjuction. That will give you the answer.


2. If you are not sure if your choice is the correct one, try to use the other. You´ll see that the meaning changes, saying something different to what you meant.




Like.


Like means 'similar to', 'the same as'.


- Like is a preposition. So it is followed by a noun (like a palace), a pronoun (like me/ like this) or -ing (like walking) 


-What a beautiful house! It's like a palace. (not 'as a palace') 
-'What does Sandra do?' 'She's a teacher, like me.' (not 'as me') 
-Be careful! The floor has been polished. It's like walking on ice. (not 'as walking') 


- You can also say 'like somebody/ something doing something'.


-'What's that noise?' 'It sounds like a baby crying.' 
-You look like your sister.


- Sometimes "like" means 'for example'. 


Some sports, like (or such as) motor racing, can be dangerous. 




As.


"As" is a conjuction. You use "as" (not like) before a subject+verb.


-I didn't move anything. I left everything as I found it. 
-They did as they promised. (=They did what they promised) 


- We also say: as you know/ as I said/ as she expected/ as I thought,...


-As you know, it's Tom's birthday next week. (=you know this already) 
-Jane failed her driving test, as she expected. (=she expected this before) 


- We use "as" with some expresions like: as usual/ as always. 


-You're late as usual. 


- As can also be used as a preposition meaning: 'in the position of', 'in the form of'.


-A few years ago I worked as a bus driver. (not 'like a bus driver') 
-We've got a garage but we haven't got a car, so we use the garage as a workshop. 
-Many English words (for example, 'work' and 'rain') can be used as verbs or nouns. 
-London is all right as a place to visit, but I wouldn't like to live there. 




For comparison.


- You use "like" for comparison and metaphors.


-I work like (not as) a horse.


- Look what happens if you don´t use it correctly!


-I work as a horse (my work is being a horse, that´s my rol.)
-I'm talking to you like your mother" (I´m not your mother but IU´m talking to you as I was!)
-I'm talking to you as your mother" ( I´m your mother and I´m talking to you.)




Note.
In U.S.A, they use "like" instead of "as" in informal speech. That is not correct.


-Nobody loves you like I do. (Nobody loves you as I do.)