More info on the benefits related to memory consumption with a 32-bit worker process

[MattiasGe]

I was intrigued by this paragraph:

One of the performance benefits of the x64 platform is that it increases virtual address space, making more memory available. We recommend that you configure IIS to use a 32-bit worker processes on 64-bit Windows. Not only its compatibility better than the native 64-bit, performance and memory consumption are also better.

Could you expand a bit on the memory consumption benefits of using a 32-bit worker process?