What is The Difference Between ALF And RPG, Programming Languages

ALF is a Logic-based Programming Language, while RPG is a Procedural Programming Language
What are Logic-based Programming Languages
Logic programming is a type of programming paradigm which is largely based on formal logic. Any program written in a logic programming language is a set of sentences in logical form, expressing facts and rules about some problem domain. (Wikipedia)
What are Procedural Programming Languages
Procedural (imperative) programming implies specifying the steps that the programs should take to reach to an intended state. A procedure is a group of statements that can be referenced through a procedure call. Procedures help in the reuse of code. Procedural programming makes the programs structured and easily traceable for program flow.
While ALF is a Logic-based Programming Language, and RPG is a Procedural Programming Language
Let us now look at the difference between the two:
What is ALF Programming Language – A brief synopsis
Algebraic Logic Functional Programming Language is a multi-paradigm programming language that is a combination of functional programming and logic programming. ALF program statements are compiled into instructions of an abstract machine. An emulator written in C executes the programs of the abstract machine.
What is RPG Programming Language – A brief synopsis
This programming language is used for business applications. It is available with the IBM’s System I midrange computers.
Sources
A Complete List of Computer Programming Languages