I've been to the Park Hyatt, I've not been to the Hilton, but the Hilton looks to be far more isolated. I.e. you would need transport to get anywhere from there.
The Park Hyatt you could walk down to the beach area - it is a walk, but do-able.

Having read Raffles review of the Hilton, I'd say the Hilton is genuinely old with unique features.
The Park Hyatt is very quaint and charming looking modern build made to look like a village. (It's like Whistler if you've ever been there - VERY NICE, but that tiny bit fake.
Depends if it being genuine matters.

Sadly I cann't comment for which is better for things away from the property.