I have looked at both (garage and photo travel/photomode)
VERY closely, and there really is a difference. Especially in the fine details. I also have my PS2 connected via S-VIDEO so that may make a difference in the amount of detail you can see on your TV.
For example: on the SUZUKI GSX-R/4 Concept, in the garage you can clearly see all the details in the brake calipers
(they are the're own part) and the vents in the brake rotors
(the little holes in the rotor) are there too. So, I took the car in to photo travel/photomode and the calipers were "painted on" the rotor and the rotor vents were completely gone.
I feel that the reasoning behind this lack of details is because: in photo travel/photomode you have to render the car, the sky box, the buildings, the people
(if there are any) as well as all the background - mountains, roads, signs, trees, guard rails, etc. In the garage you only have a car and some lighting - no more.
Also let's say that the old PS2 HW has issues
(like render time) on anything above a certain poly count. Out in the "world", with all the surroundings, the poly count, as well as textures can get pretty high. Now take it in the garage and all you have to view is the car - none of the other stuff. The designers probably figured that most players would like to press the shutter and see a pic in a couple of seconds as opposed to waiting 20, 30 seconds or more for the HW to render a high-poly scene, so they opted for the quick route as opposed to the quality
(time intensive) one.
I guess I just wish that they let me control which car to use. Like having a photo travel/ProPhotomode where the render time takes a while but the results are much better because they use the highest poly models.
I'm all about the quality - even in my "fake" photographs!
-= Vicious =- VP