I've been a regular visitor to PGA since the park first opened back in 1976, and got the chance to visit SFGAM 3yrs ago. Visiting the Illinois park was like entering a time machine for me, so much of the original park was still intact, as far as themed buildings and classic rides, many other little details I forgot ever once existed in my hometown park. Even with all the new rides and additions, the atmosphere of the original Marriott parks was still present at SFGAM. PGA on the otherhand has almost been completely remodeled with tacky gaudy ugly Paramount theming/advertising, so many original and classic rides and landscaping ripped out, it feels and looks nothing like the original park.
Both still do feature the double carousel, Logger's Run, Demon(although PGA's has been Paramountized, none of the effects have been maintained, headchopper rocks around the verticles have been removed, and the slammer first drop was replaced with a boring, no airtime standard 45 degree drop). Triple Play is still in both parks, as is the Rue Le Dodge bumper cars, but that's about it for rides(cant recall if SFGAM still had Orleans Orbit).
The first part of Orleans Place is still about the same, but as soon as you go under the train tressle, PGA's has been rethemed to a 50's area. Most of the building in Hometown Square are still the same, but with the TA2K now under construction at PGA in that area, I'm sure that will all change as well. These are the only similarities I can recall that still remain between the 2 once identical parks.