Visual Studio for Mac is not a port of Visual Studio for Windows; it's a rebranded version of Xamarin Studio integrated development environment (IDE) that will work on the Mac. (Microsoft bought mobile-tool vendor Xamarin in February 2016.) Visual Studio for Mac is available as of today as a preview for download.
Visual Studio 2017 is the official name of the product Microsoft has been calling "Visual Studio Next" and/or codename "VS '15'." As of today, a near-final Release Candidate version of that product is available to testers. The RC includes a few brand-new features, but is mostly complete at this point. Officials told me this week that the final/general availability version of Visual Studio 2017 would be out in early 2017.
Visual Studio for Mac will include IntelliSense and refactoring via the Roslyn Compiler platform. It will use MSBuild and the same debugger engines for Xamarin and .NET Core apps, as well as the same designers for Xamarin.iOS and Xamarin.Android.
Visual Studio 2017 for Windows also is relying on the "Roslyn" work to rearchitect the C# and Visual Basic compilers. The coming release includes enhancements in refactorings, code generation, code analysis, navigation, testing, and debugging, officials said.
Other Connect() announcements today included a preview of a new Visual Studio Mobile Center, and general availability of both Visual Studio Team Foundation server 2017 and Azure Application Insights.
Visual Studio Mobile Center is a portal that is meant to help developers build, test, distribute, and monitor apps built in Objective-C, Swift, Java, Xamarin, and React Native for Android, iOS, and Windows devices. Documentation for the new Mobile Center is here.
Samsung also is releasing a preview of Visual Studio Tools for the Tizen operating system, which will allow developers to build apps for Tizen running on Samsung TVs, wearables, mobile, and other IoT devices.