Difference between const and val

Both are immutable but...

const is compile time constants. Meaning that their value has to be assigned during compile time, unlike val, where it can be done at runtime.

This means, that consts can never be assigned to a function or any class constructor, but only to a String or primitive.

For example:

const val foo = complexFunctionCall() //Not okay 

val fooVal = complexFunctionCall() //Okay 

 const val bar = "Hello world" //Also okay

const val obj = MyClass() // Not okay

val obj = MyClass() //okay 

Reference

https://stackoverflow.com/a/37596023/2409495