Pros and Cons of COM reference and DLL reference

I would like to know pros and cons of COM object reference and DLL reference.

Say,I'm writing a tool to do some operation with MS Excel, should i add the reference of the Excel in .Net tab or COM components tab of Add Reference dialog box.

In the below link,it was said like we can use Embed Interop Types property to embed the COM objects required in the referenced DLL.

https://social.msdn.microsoft.com/Forums/vstudio/en-US/39edc2f3-781b-48c6-8e5f-f170ef00b10e/why-does-the-embed-interop-types-option-not-generate-the-appropriate-dispidattributes-in-some?forum=clr

How it will impact the application?