Lambda Expression: As we know, syntax of Kotlin lambdas is similar to Java Lambdas. A function without name is called anonymous function. For lambda expression we can say that it is anonymous function. A lambda expression is always surrounded by curly braces, argument declarations go inside curly braces and have optional type annotations, the code_body goes after an arrow -> sign. If the inferred return type of the lambda is not Unit, then the last expression inside the lambda body is treated as return value.
Higher-Order Function: In Kotlin, a function which can accept a function as parameter or can return a function is called Higher-Order function. Instead of Integer, String or Array as a parameter to function, we will pass anonymous function or lambdas. Frequently, lambdas are passed as parameter in Kotlin functions for the convenience.
Happy Coding :-)