I assume by DLR you mean the
Disneyland Resort in Anaheim?
The major differences at HKDL are of course Toy Story Land, Grizzly Gulch and Mystic Manor, as you've already pointed out. There's also a few things which are the same or similar on other Disney properties (but not DLR) like Mickey's Philharmagic, The Golden Mickeys, and Festival of the Lion King. I believe Stitch Encounter is also something a little bit different, comparable to Turtle Talk with Crush at WDW.
Their Jungle Cruise has a few additions to the one at DLR, but some find the language barrier to be a problem. Personally I didn't have any issues with it. Tarzan's treehouse is exactly the same as the one at DLR - you just have to take the raft to get there, and you go through a cave with a waterfall on the way through. Of course, the view is a bit different
I haven't done Winnie the Pooh at DLR so I can't say if there's any difference there, and I didn't do IASW at HKDL, so I don't know about that either. I know that it's different from the WDW version, but I think with the latest update to the DLR version with the Disney characters in it, it's pretty similar to HK.
Rides/attractions that seem to be pretty similar to their DLR counterparts include Space Mountain, Buzz Lightyear, Dumbo, Teacups, and Autopia is pretty similar although the HK version has electric cars.
I enjoyed Fantasy Gardens for character greetings, and got a picture with Donald in his Chinese outfit. I also really enjoyed the parade and would highly recommend making it a priority. The fireworks are a good show too, although it's not as long a show as the ones at DLR, and there are more special effect type fireworks involving the castle than the big round ones that explode high in the sky (hope you know what I mean). Definitely worth being front on to the castle for them if you can to get the full effect of the symmetry.
As far as souvenirs go, the main ones that spring to mind in HK are the tins of biscuits/lollies. I really loved them and stocked up on a few! There were also a few sets of small ones that were inexpensive gifts for my work colleagues. The confectionery shop is basically full of them, and I don't remember seeing anything like them in the US. Some of them are fairly Chinese looking in design too. Many of the other souvenirs were the same as what you'd get at any other Disney park.
If you have a full from opening to close you should be able to fit most things in, depending on crowds. It's only a small park. We didn't find any eateries that really stood out, but I would recommend trying a Minnie ice-cream bar
