There is no difference if you limit the use of the tool to not use these features.
In my eyes, it's a philosophical difference between the two, Flow can be more easily integrated into an existing codebase by just adding //@flow at the top the file and has no features which can affect runtime code. Whereas TypeScript tries to be a different language altogether that uses a new file extension, adds new features, and has its own compiler.
Typescript doesn't try to be a different language. It tries to be an exact superset of JS: JS with annotations. And you can absolutely implement what you linked, it exists and it's called tsc: the "compiler" you're somehow upset Typescript has (this + checking types is all it does!). Babel does it natively.
Enums are a fair point, those aren't in the ES specs (though I suspect at some point they will be). However, they're an incredible addition and they really are just syntactic sugar for a more complex type of object.
BTW, typescript supports jsdoc-style annotations, and --allowjs even lets it typecheck javascript code. It also supports more, because nobody actually only wants those things; they're not that great on their own.
Not sure where you got the idea that I'm upset that TS has a compiler, I'm just pointing out my perspective on the differences between the two tools. I use both on a daily basis.
You might not think the differences is a big deal, but affecting runtime code is a pretty major line to cross. Not that there is anything inherently wrong with that, but at that point it becomes a different tool, in my opinion.
No I get you, being able to map the exact code is important. But I think what's happening is you're confused about the ES20XX translation layers. Those aren't at the typescript level, they're at the Babel level … it just so happens that tsc supports that bit, but it's my understanding that this will be going away at some point (eg. typescript will move to only doing the typechecking, and leaving babel to only do the compiling).
enums are a tiny, extremely useful and extremely optional part of the language and they don't warrant this label of "philosophical difference", IMO.
In my eyes, it's a philosophical difference between the two, Flow can be more easily integrated into an existing codebase by just adding //@flow at the top the file and has no features which can affect runtime code. Whereas TypeScript tries to be a different language altogether that uses a new file extension, adds new features, and has its own compiler.
When you can implement a tool like this using TS, let me know https://github.com/flowtype/flow-remove-types