[vtbassmatt]

Good questions. TFS is a whole suite of services: 2 version control systems (TFVC and Git), work item tracking, build orchestration, package management, and more. VSTS is the roughly-analogous cloud-hosted version.

I'd have to dig up the link: a few years ago our VP had a good blog post on why we chose to add a Git server to our offering. TFVC is a classic centralized version control system. When we wanted to add a distributed version control, we looked at rolling our own but ultimately concluded that it was better to adopt the de facto standard.

[FLGMwt]

  ultimately concluded that it was better to adopt the de facto standard

Thank you for that : )