Difference between Like and As

Key Difference: The primary difference between ‘like’ and ‘as’ is the fact that ‘like’ is used to make a direct comparison, whereas ‘as’ is used to link two phrases together which are related in some way or manner. Another rule to remember is that, ‘like’ is most commonly used as a preposition, whereas ‘as’ is most commonly used as an adverb.

Like ‘Like’ and ‘As’ are two very similar words in the English language. Both are used for comparison, hence it can be quite confusing as to when to use which one. It is also due to this that many people think the two terms are the same. However, that is not exactly true. The two are used as two completely different terms. Though they do have an overlapping function, the two are distinct terms that are used in a variety of different ways.

The primary difference between ‘like’ and ‘as’ is the fact that ‘like’ is used to make a direct comparison, whereas ‘as’ is used to link two phrases together which are related in some way or manner. For example: “His ball is like mine.” This means that his ball is very similar to my ball, most likely in appearance. However, if ‘like’ is replaced with ‘as’, then the meaning of the sentence changes. Such as “his ball is as mine.” The sentence here sounds wordy and incorrect, because the context of the phrase has changed. It is no longer a direct comparison but more of a generalization. Hence, in order to be specific, the sentence should be “his ball is as big as mine.” This gives it more of a context. It should be noted that ‘as’ is more commonly used to make comparisons in a specific manner or to an extent of something.

Another rule to remember is that, ‘like’ is most commonly used as a preposition, whereas ‘as’ is most commonly used as an adverb. This means that the use of ‘like’ should be followed by a noun or pronoun. We use ‘as’ when the second term of the comparison is a verb, a clause or a preposition.

In addition to being used to make comparisons, the words have other usage as well. ‘As’ is also used to indicate that something happens during the time when something else is taking place. For example: “she was reading, as it rained outside.” It is also more commonly used in the context of the function of a person or object. For example: He works as a music teacher. In these contexts, ‘like’ would be completely incorrect and would drastically change the meaning of the sentence. “She was reading, like it rained outside” or “He works like a music teacher” make no grammatical sense whatsoever.

Thought the difference between ‘like’ and ‘as’ can seem confusing, it gets easier with a little bit of practice and experience. However, in the meanwhile a general rule of thumb which might make it easier to distinguish the two is to remember to use like with nouns and pronouns, while as with clauses and verbs.

Rule of Thumb:

like + noun or pronoun
as if/ as though + clauses and verbs

Comparison between ‘Like’ and ‘As’:

	Like	As
Definition (Oxford Dictionaries)	Having the same characteristics or qualities as; similar to. Used to draw attention to the nature of an action or event. Such as; for example. In the same way that; as. Used with reference to a person or thing of the same kind as another.	Used in comparisons to refer to the extent or degree of something. Used to indicate that something happens during the time when something else is taking place. Used to indicate by comparison the way that something happens or is done. Used to refer to the function or character that someone or something has.
Description	Used to make a direct comparison between two things.	Used to connect two words, phrases, or clauses that have something in common.
Uses	Like is mainly used as a comparison.	As is mainly used to describe or refer to the manner or condition of the things.
Type	Preposition Conjunction Noun	Adverb Conjunction Preposition
Utilization	Comparison. To compare two or more things.	Comparison. To compare two or more things. To connect two things that have something in common.
Examples	It looks like it will rain. Dave looks like his father. Don’t act like him! She plays the piano like her sister. He is just like his brother.	She is as beautiful as an actress. She works as a teacher. It started raining, as I said it will. They went to the party as they were.

Reference: Oxford Dictionaries (Like, As), EnglishGrammar, ToLearnEnglish, The Economist
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