As if and as though

take from : basic english usage by Michael Swan

as if/though + subject + present/past verb as if/though + subject + past verb with present meaning

1. As if and as though mean the same.

We use them to say what situation in seem like

It looks as if/though it’s going to rain

I felt as if/though I was dying

2. We can use a past tense with a present meaning after as if/though. This means that the idea is “unreal”.

Compare:

He looks as if he’s rich (Perhaps he is rich)

She talks as if she was rich (but she isn’t)

We can use were when express “unreal” idea after as if/though. This is common in a formal style.

She talks as if she was rich

3. Like is often used instead of as if/though, especially in American English. This is very formal.

It looks like it’s going to rain.