kotlin coroutine val vs fun

Question

I'm new learner to coroutine and Kotlin. Why do I obtain different results, case 1 and 2 below?

fun main(args: Array<String>) = runBlocking {
    fun a() = async(CommonPool) {
        println("start A")
        delay(1000)
        println("finish A")
    }

    fun b() = async(CommonPool) {
        println("start B")
        delay(1000)
        println("finish B")
    }

    //case 1
    a().await()
    b().await()

    //case 2
    val A = a()
    val B = b()
    A.await()
    B.await()
}

Is this val style coding basic?

Answer 1

The case 1 is equivalent to

val A = a()
await(A)
val B = b()
await(B)

That is, you start A , await it (here the coroutine suspends), and only then you start B , thus A and B are executed sequentially, not simultaneously.

In case 2 you start both A and B and only then the coroutine suspends waiting for A and B .