Wich one do You mean is heavier ?
The WM9 bracelet should be heavier because it has solid midlinks.
And Rolex has now after 25 years done a GOOD bracelet and clasp ( on almost ALL their watches but NOT for the Submariner, but the new sub will of course have it ! ) , I mean the original bracelet for a rolex is so bad when it comes to "feeling" because it is NOT so solid sounds so cheap when moving Your wrist fast !
It works OK BUT the quality of it is so LOW if You for example look on the IWC braclets where the bracelet IS a WORK OF ART !
I like the braclet on my WM9 MORE the on on genuine Seadweller !