With Azure functions what is the difference of using .net 6 and .net 6 isolated?
1st Major term between them is .NET 6 belongs to In Process and Isolated belongs to Out-of-Process runtime of the Azure Functions.
Azure Functions .NET Isolated Process official documentation provides you the context on why to use Isolated and benefits of it over In-Process Runtime Languages like .NET 6.
Few Points on .NET 6 vs .NET 6 Isolated on Azure Functions:
Tight coupling between the host process and the .NET Function in In-Process runtime because .NET Class libraries share binding APIs & types.
Isolated .NET Function Project is an console app that gives you access to the star-up of the function app.
Another Microsoft Doc providing the details on functional & behavioral differences wise for running the functions on out-of-process and in-process.