Here's the changes I would make, though I might be missing some stuff:
- Alien ships
- Bajoran: 'Bajoran fighter' and 'Bajoran raider' should be made one folder, they're the same ship
- Borg: 'Borg cube' and 'Borg tetragon' are both different concept stages of the First Contact Borg Cube, I'd make them one folder named 'Borg FC cube' or something like that
- Jem'Hadar 1: The first three images on the 'Jem'Hadar attack vessel' folder are early concepts for the Jem'Hadar battle cruiser, so they should go on that folder. The fourth image should go on the 'battleship' folder. The remaining image is an exploratory concept of the 'Fighter', it should go there
- Jem'Hadar 2: The first two images in the 'Warship' folder are early concepts for the 'Fighter', should go on that folder. The third image belongs to the 'Battle cruiser' folder
- Jem'Hadar 3: The final image in the 'Battleship' folder should go on the 'Battle cruiser' folder.
- Jem'Hadar 4: The 'Dominion ship concept, Curry - 1994 04' image on the 'Alien ships' folder is yet another exploratory concept for what became the JH Fighter
- Kazon: The two concept images listed as 'unknown' are by Daren Dochterman. He did several concept pieces for the Voyager pilot episode
- Klingon 1: On the 'Bird of Prey' folder, the third image (the one by Eaves) should be taken out of the folder and into the 'Klingon' one. It's from DS9, for a larger BoP that was never built as they ended up reusing the Negh'Var model from TNG instead.
- Klingon 2: Images 2 and 3 on the 'Klingon' folder are interior concept sketches for the Bird of Prey, so they should go on that folder. Image 4 on the same folder is an early concept of the 'Vor'cha', should go on that folder.
- Schimitar: It's written Scimitar.
- Son'a: The first image in the 'Battleship' folder is actually the Scimitar
- Void ships: The final image in the folder is a repeat on the 'Chaotic Space Hulk' ship, which has its own folder
- Costumes and characters
- DS9: The 4th image on the folder goes on the top Costumes folder, as it's part of the same campaign as the other female portraits by Eaves
- STII - The Wrath of Khan: The first image on the folder belongs on the STIII folder
- Locations:
-Ba'Ku: Shouldn't the first image in the folder be better placed in the 'Costumes' folder?
-Cardassian: The final image in the folder is a concept piece for DS9's ore processing center, should go on the appropriate Space stations>DS9>DS9 interiors folder
- Earth: The Probert painting (second image) is technically not concept art, but a painting he did for the Ships of the Line calendar in 2009.
- Planet of the Titans: The first image is actually what the interior of the Enterprise was meant to be, so it should go on the appropriate folder (there doesn't seem to be a folder for the Planet of the Titans Enterprise concepts?)
- Props: There's a ton in there, and my knowledge isn't as good off the top of my head to get into it lol
- Shuttles:
- On the main folder, the fourth image is by Eaves, not Martin. It's on the Final Frontier shuttles. Images 5 and 6 (Kazon shuttle) are by Dochterman. Image 9 should go on the "TMP Shuttle concepts" folder, and that folder should be renamed "Planet of the Titans shuttle concepts"
- Federation Scoutship: Images 2 and 3 belong on the 'Type 11 shuttle' folder
- Space stations:
- On the main folder, you got an image of Farpoint here instead of on the 'Farpoint' folder in 'Locations'. Also, the 5th image is a repeat as it's already found inside the 'Federation' subfolder
- Starfleet ships:
- Images 1 and 3 in the main folder are fan designs, I don't know how useful they are here. Image 4 is an early concept art of the Excelsior by Nilo-Rodis, should go on the appropriate subfolder.
- Cargo ships: The third image is from a Probert painting for the Ships of the Line calendar in 2015
- Enterprise-A: The folder should be renamed 'Enterprise refit'
- Enterprise-A interiors: Image 15 in the folder is actually the inside of the travel pod, should go on the appropriate Shuttles>travel pod folder. Image 16 is from the orbital office complex, should go on the Space Stations>orbital office folder.
- Enterprise - TAS: Already mentioned by @BK613
- NX era ships: The first three images in the folder are of the Axanar cargo ship, they should have their own folder in the 'Alien ships' section.
- Picard era: First image is a non-starfleet design, should go on the 'Alien ships' section.
- Runabout interiors: Images 10 and 11 are concepts for the Santa Maria from DS9:"Paradise", should be in the top 'Starfleet ships' folder.
- Voyager final: Image 3 on the folder should go on the 'Voyager concepts' folder.
