It's not a difference in marketing. Types anotations are part of Python, but not of JavaScript. CPython will happily run a program with type anotations, V8 will

It's not a difference in marketing. Types anotations are part of Python, but not of JavaScript. CPython will happily run a program with type anotations, V8 will fail to parse Typescript. You could draw similarities with using Typescript to check JSDoc comments and MyPy to check Python 2.7 comments, but that's again because type hints are neither part of Python 2.7, nor JavaScript.