The two hotels share a driveway and a spa, but other than that they're completely separate, so I've never been over to the Conrad side.
From the pictures the two hotels seem very similar in design. We like the All-Inclusive part of the Hilton, and the food and drinks are top notch - so good.
I'm sure you'll have a great time - it's one of the prettiest places in the world, we love it there.