GameMaker uses its own custom programming language. Construct allows coding in JavaScript which is widely used across the software industry and is the kind of language you can get a job in. It is also a more mature language and has far more features like classes, arrow functions, async functions, generator functions and iterators, template strings, and lots more, and is still getting new features, like the more recent optional chaining (?.) and nullish coalescing (??) operators.