Object-Oriented Programming (OOP) views software as a collection of interacting objects, each with its own data and behavior. It’s well-suited for modeling real-world entities and complex systems. For example, a car is an object with properties like color and speed, and it can do things like start and stop. This approach is particularly effective in scenarios demanding complex systems with interrelated components. For example, graphical user interfaces and large scale enterprise applications.

Functional Programming (FP) treats computation as the evaluation of mathematical functions. It uses functions that take inputs and produce outputs. Think of a calculator: you input numbers, and it outputs the result. It is used in applications requiring high levels of  testability and efficiency. E.g., financial systems, data analysis, parallel computing, etc.