.NET 3.5 with Service Pack 1, .NET 3.5 SP1, .NET 3.5.1, .NET 3.51. Are they all the same thing?

Question

I'm researching version info about .NET Framework 3.5 and I have 3 questions.

1) My web searches turned up several names: .NET 3.5 with Service Pack 1, .NET 3.5 SP1, .NET 3.5.1, .NET 3.51. Are they all the same thing?

2) My Registry shows I have .NET 3.5 SP1 installed (version 3.5.30729.4926). If I use Visual Studio 2010 to develop an app on this computer, would the app run in .NET 3.5 without any problems? Visual Studio C# doesn't seem to have a Target Framework selection specifically for .NET 3.5 SP1.

3) What's generally considered as the most widely installed/used version of .NET now? .NET Framework 3.5 SP1 or 4.0?

Thanks in advance for sharing your knowledge.

Answer 1

Actually .Net 3.5.1. is the version that ships IN Windows 7 and Windows Server 2008 R2, and is installed as a feature (not as a standalone msi like other frameworks). So you're wrong Jon Skeet.

Whether this is functionally the same as .Net 3.5 SP1 or not I've yet to determine..!

Answer 2

As Microsoft say "The .NET Framework 3.5 SP1 (also referred to as .NET Framework 3.5.1)", presumably .NET 3.5 SP1 and 3.5.1 are identical and have the same functionality.

Source: How to install/enable .Net 3.5 SP1 on Windows Server 2008 R2