Unlinked product / campaign
An unlinked product or campaign doesn't need the brand's name to be recognized, so they can capture information on their own. A clear example is "Galaxy S4". If a comment has "Galaxy S4" in it, it is talking about the mobile phone model of the brand Samsung and the comments the platform will search for and capture, will talk about Samsung Galaxy S4 even if we didn't indicate to the platform (indicating entity linked) that comments must have the word Samsung.
Unlinked product / Samsung
Linked product / campaign
On the contrary, a product or campaign linked is one that doesn't have a unique reference to a brand and therefore, they need their brand to be identified. If we leave them as unlinked the search could capture comments that aren't relevant for your analysis.
e.g.: If we look for “fiesta”, we could find comments talking about “Fiesta de cumpleaños” or “Fiesta de fin de año”. Instead if we indicate, the product or campaign are Linked, then the system relate the word “Fiesta” with the brand. As a result only will show comments where the words "Ford" and "Fiesta" appear.
Linked product / Ford