What are Trophy and Salvage items?

What is the purpose of these items? I just don't get it.

Are salvage items there only to be salvaged?

Solution 1:

Trophy items (with text in grey) are all sold with the "sell junk" option at merchants. So I figure that, generally speaking, that's their purpose.

Salvage items can also be sold, but the difference is that you can get crafting materials applying a salvage kit on them.

Other trophy items won't appear as salvageable, but they won't be considered junk either (their text will be white instead of grey), because some NPC collects them (indicated on the item description). You can return them to the NPC that claims them or you can sell them.