So many people use like and as if interchangeably, you’d think they mean the same thing. I even see good writers doing it. He ran like a ghost was chasing him, for instance. The problem is, this is not correct English.
Like is a preposition. It shows the relationship between two nouns. As is a conjunction. It joins two phrases together. Saying “He ran like a ghost was chasing him” is incorrect because “He ran” and “a ghost was chasing him” are phrases. However, “He ran as if a ghost was chasing him” is correct because we are linking two phrases, “He ran” with “A ghost was chasing him.” If you want to use like, it would be more correct to say something similar to “He ran like a man chased by a ghost.” The preposition like is used to compare “He” with “A man chased by a ghost.” .There’s a good quick and dirty tip on how to know which is correct. If no verb follows, like is the correct choice. Otherwise, consider using as if.
There is one slight qualification to this. People are using “Like” in place of “As if” so often, it is tending to become standard use. The rule makers appear to be giving up. In my opinion, it’s best to not allow bad writing to take the place of good writing, but you’re the writer and you can write anyway you like. If you use the correct choice, however, you will have a better chance of impressing writing professionals.