What do the symbols on the workshop items mean?

I recently started playing Fallout 4 again after binging it for the first two months it was out, and I have all of the DLC. I noticed a ton of new workshop items that I could build, but some of them have icons (deathclaw head, gear, etc) on them and I'm not quite sure what they mean. What do these icons signify?

These icons simply denote what DLC each item was part of. From this post:

Mechanist mask:automatron specific content, such as the eyebot pod or robot workbench.

Deathclaw head: wasteland workshop.

Boat icon: Far Harbor.

Wrench icon: contraptions.

Vault door: vault tec workshop.

Plus icon: more then one dlc's content in this section.

Additionally, there is an M icon that signifies content added by mods.