We're three twenty-somethings visiting WDW in May/June -- my boyfriend and I are
Disneyland Annual Passholders and visit about once a month. Our friend has visited with us twice in the last few months.
Which of these bi-coastal rides are different enough at WDW that they're worth riding, even with our frequent trips to DL?
Big Thunder Mountain Railroad
Buzz Lightyear's Space Ranger Spin
Enchanted Tiki Room
Haunted Mansion
It's a Small World
Jungle Cruise
The Many Adventures of Winnie the Pooh
Peter Pan's Flight
Pirates of the Caribbean
Space Mountain
Splash Mountain
Under the Sea ~ Journey of The Little Mermaid
Soarin'
Fantasmic!
Star Tours: The Adventures Continue
Toy Story Mania!
As I said in previous post, we are in your same situation. I thought it may be useful to give you more details on the specific rides you mentioned. My recommendation is that you experience everything at least once. It is fun to have the "deja vu" feeling on a ride that is similar, but different that what you're used to.
BTM
I would say it is a wash. DLR has the explosion scene in the lift hill. WDW has a much more detailed queue.
BLSRS
DLR is much better. WDW version has blaster affixed to ride vehicle. Once you experience tethered blaster at DLR, the WDW version seems constrained.
ETR
Mentioned in last note. Very similar show. Show are is larger and less intimate than DLR. Preshow is different.
iasw
WDW got the "short straw". But it is fun to see some of the scenes and items that are in WDW and not @ DLR.
JC
I think it is a wash, with slight edge to WDW. JC @ DLR can be dependent upon how good your skipper is. DLR seems to have better entertainment than WDW, so you have a greater chance your JC skipper @ DLR is an aspiring comedian on the weekend. WDW version has indoor scenes missing from DLR version.
TMAWtP
I think this is a wash, but WDW version is a bit better. My lack of detail shows just how memorable this was for me. WDW queue has interesting interactive queue elements.
PPF
Same as Pooh. DLR PPF got some projection upgrades that haven't made it to WDW.
PotC
Agree with previous poster.
Space
All the darkness of DLR SM, all of the back injuries from Matterhorn. The track is rough. Highly recommend you brace yourself by pushing your back into the ride vehicle to provide extra support. Hint: Ride camera is first turn out of station. Now you know not to have a stupid look on your face on your first ride. Another hint, look at the electronic exit billboards. The system monitors Magic Bands and will use your name in the ads. It doesn't happen all of the time, so keep an eye out, and don't be disappointed if your name doesn't show up.
Splash
WDW rules. More comfortable. Better AA.
Soarin'
Exact same film. We skipped it. Saved more time for FEA, Test Track and Mission: SPACE.
Fantasmic!
I'll be in the minority here, but I enjoyed F! @ WDW. I totally get what everyone has to say about how DLR is better than WDW, and I agree. I agree that DLR is more intimate and having full sized Twain is way more impressive. But... I miss the old soundtrack from the DLR F!, before the last upgrade. The WDW F! will make you nostalgic for the DLR version.
Star Tours:
Exactly the same. There were only four rides at DHS when we were there, so why not?

The only thing I remember is the faux AT-AT where you could see exposed framework from inside the queue. The rest of the ride is the same as DLR.
TSM
Exact same ride. See four ride comment. We rode it to see the differences in the queue. WDW queue is better. TSMM @ WDW has three tracks. The queues for two tracks are together, and then there is another track queue across the way at
Pixar Place. No idea if third track queue is as detailed as first two. But I'd recommend one ride.
Enjoy your trip!