XML and PDF File Compare and Update

I have two documents: 1 XML file and 1 PDF file. The PDF File is the 4000 page Data Dictionary for the XML file fields. I want to compare the XML field Name (IE: A00030) to the Data Dictionary file. If there is a match, take the item description from the dictionary and insert it as a comment in the XML file next to the field name.

I am new to UI Path but this sounds like a classic automation utilization case. If there are any suggestions on how I might accomplish this, I would appreciate it.