Does it exist both an managed and unmanaged version of ODP .Net version 4.x?
Can you please enlighten me on that question and perhaps point to some Oracle documentation describing the different Oracle Data Providers for .NET and the differences between them?
ODP.NET documentation is the best place. Near the end of Chapter 1, the API differences are documented. In Chapter 2, the configuration difference are noted. Chapter 3 covers the major functionality differences, though most people can deduce this already based on the API and configuration differences.