The second command, dotnet run checks the current directory for a csproj file, and if there is exactly one of them, then the project is compiled using the new Roslyn compiler using the Debug configuration and An圜PU processor target. The project file is used by the Roslyn compiler to make decisions about how to compile and link the results.
The first command, dotnet new console tells the tool to create a new csproj (aka C# Project) file in the current directory, named the same as the current directory. The dotnet tool is a wrapper for several other tools such as the nuget package manager and msbuild build system.
