I had a Motorola Backflip before, and while I hated it for a lot of reasons, one thing I liked was the way the Picture Viewer worked. The default one let me add tags and sort images. I traded it in for a Palm Pre Plus, and recently upgraded again to an HTC Inspire 4G. I thought that since I was going back to an Android phone, I would have this same feature available, but it seems these features I actually liked on the Backflip are not on the Inspire.
Does the default Image viewer differ between different phone vendors, even on the same OS platform?
The short answer: Yes, they can, and often are, different.
Android has a lot of core applications and functionality, but a lot of manufacturers add to, alter, and replace some of that. For instance, HTC has their Sense UI and Motorola has their Motorola Blur UI. They customize various parts of the system like the Lock Screen, the Home Launcher, the Clock application, and the Picture viewing application. And generally you can’ use them on other devices (the Sense UI, for instance, is deeply integrated into the HTC Roms, so you can’t take their Clock application, for example, and use it on a non-HTC ROM).
My suggestion is that you look in the Android Market for something comparable to the picture viewer that you had on your Backflip.