All these conjunctions are used to show how someone or something feels, looks, sounds, etc. In this case they are absolutely interchangeable.
The crowd is gathering at the square. They sound like they are going to start walking along the streets and crushing everything on their way.
Take off this T-shirt immediately. It looks as if someone’s washed the floor with it.
I climbed the stairs to the second floor only butI got out of breath. I feel as though it’s the tenth floor.
Like/ as if/ as though are often used in impersonal sentences.
It looks as if/ as though it’s going to rain soon.
It sounds like a good idea!
As if/ as though are used to talk about an imaginary situation which isn’t true but possible or to say how something or someone looks based on the information that you know.
Let’s pretend as if we’ve never heard him say that.
Mike looks as though he’s caught a cold.
When we want to compare something in a way that says it is not true, or when the situation is unreal, doubtful or improbable, in that case as if/ as though are used with past subjunctive though we speak about the present moment. Like cannot be used here.
He’s behaving as if he were a world champion.
She looks as though she was a queen of the ball.
He’s driving as though he were a street racer.
If something is true or possible we use present tense to express present time.
He looks like he has been working all day.
Her voice sounds as though she has a sore throat.
The past perfect subjunctive is used to express an unreal situation in the past.
He seemed as if he hadn’t eaten for several days.
