Well, before we actually get to the difference, let’s start with a quote about Grammar: Arguments over grammar and style are often as fierce as those over IBM versus Mac, and as fruitless as Coke versus Pepsi and boxers versus briefs.- Jack Lynch

Grammar differences are peculiar, hard to understand at times and even harder to agree with. But a man’s got to do what he has got to do.

Use of Like:  When comparing clauses, that is a part of sentence that contains a subject and a verb, we must use “as” instead of “like.” And use ‘like’ when the comparison only includes a subject.
For example:
Usage of Like: “John sings like his father.
Usage of Like: “John sings as his father does.
Example for incorrect usage: “John sings like his father does.

The last sentence is incorrect as a verb (that is does) cannot be used when we use like.

Another example to clarify matters:
Incorrect – Ram and Shyam, as their mother Seema, are extremely smart.
Correct – Ram and Shyam, like their mother Seema, are extremely smart.

The proper way to differentiate between like and as is to use like when no verb follows. For example, Heena cries like a baby or. Keep in mind that when we use like, the words that come after are generally simple.

If the clause that comes next includes a verb, then you should use as. For example, Heena cries as if she were a child. Notice that when I use as, the words that come after tend to be more complex and give a feel of a sentence, something that is missing with like.

Hope the difference between the two is clear now.