The LMM ride in MK is more like Nemo, but themed to LMM - clamshells and all. Music and animatronics while you ride through.
The HS is a stage show that combines video, puppets and some live singing.
We like the show at HS, but will not wait more than 10 minutes to see as it is a nice show but not one of the best at WDW. We went on the MK ride last year and thought it was well done and will go on again this year a few times I am sure.