Did my homework and searched for this, but:
What is the difference between "Source File Name" and "Source File ID."
And how do they relate to Media Composer's Columns called "Source File" and "Source Path"
Source File Name is the name of the actual file that is linked or imported including the extension. So if you linked to a ProRes file called "firstshot.mov" that's what you would see in the "Source File" column.
Source File ID is something that Avid creates internally when importing that as far as I know, we have not comtrol over. Source Path is the where the file was when it was linked.