Just pulled the images into photoshop and layered them over one another, scaled them to the same size, and saw nearly zero difference in the models (even the texturing looks to be the same). It may have more vertices or something like that, but they were definitely created from the same original model (the smaller spikes further up on the tail even matched up identically). The beak might be slightly more "squished" but it's hard to tell because the angles aren't 100% identical, personally I think even that is the same or so close it's not really up for debate. The comment about them being "slimmer" is incorrect, as I have just looked at them pixel-for-pixel on top of one another and the bodies match perfectly (of course in game this will probably vary depending what your graphics are set to, I.E 16:9 vs 16:10 creates slimmer or wider models)
That being said... I have no problem with this, for the reasons stated before - it's an FF mob, we expect to see heavy crossover of mobs throughout the series. I would like to see some different "interpretations" of these mobs though, for example - in new areas it'd be nice to see colibri that aren't simply re-colors, but instead take on a different appearance in other ways. Some examples might be giving different breeds larger spikes, shorter beaks, giant wings, multiple wings, multiple tails, no tail, wide-finned tails, etc.
As long as they weren't just coppied in for the sake of a fillter-quest that involves killing 15 colibri or "go kill colibri and bring me 15 feathers" etc... I'm fine with it. I have this lingering feeling that we are going to see mobs just copypastad into the game en-masse and shown to the public in the next few months simply to fill grind quest holes as more of the game's "content" is "filled in".
What frustrates me is that FFXI had this really open world feel to it where you could explore and kill as you pleased, with some events here and there to really give you an experience to remember and challenges to overcome with friends. What I don't want to see is the game cheapened by eliminating the "go out and explore the world" feeling and replacing it with "do this fetch-quest then the next fetch-quest, then the next-fetch quest, and eventually you'll see everything out of necessity instead of curiosity".
I do feel FFXI should have had a "few" more obvious quest options available from levels 1-30 to just showcase what the game had to offer for a new player, but after that I'd like to just be "set free" into the world where I can explore what I want. I'm hoping FFXIV takes that approach, but from what I've seen so far, it doesn't look likely.
Posting from just above the generator.