The following official links lead to the Microsoft Download Center for the different iterations of the 4.5 series:
These are "empty" versions of the libraries that contain only the metadata. They tell your compiler and Visual Studio which classes and methods are available in .NET 4.5. net framework 45 developer pack link
Unlike a standard runtime installer, the developer pack is a bundled installer that provides several key components for your development environment: The following official links lead to the Microsoft
– Note: This is the redistributable runtime for end-users, not the full developer pack. What is Included in the Developer Pack? net framework 45 developer pack link
– Used specifically for legacy projects that must target the 4.5.1 revision.