The additional back-panel binding-post connections are for your convenience. The number of them does not tell you how many amplifiers are contained in the receiver, nor does it tell you how many channels of audio can be simultaneously processed. Several manufacturers (Pioneer is another) provide more connections than can be used simultaneously. In this case, the X5200W has only 9 internal amps. If you want to drive more speakers than that (up to 13), you'll need to provide external amplifiers. During setup you tell the receiver which binding posts are to be used. When you change the speaker configuration, whether during the initial setup or when playing different types of soundtracks (e.g. stereo or multichannel), you can hear relays switching which connect or disconnect amps and binding posts.
Most of the differences between the Denon X5200W and the Marantz SR7009 receivers are trivial. They're made by the same company, with common digital circuitry but different analog circuits. Both support up to 12 simultaneously active channels (including the subwoofer/LFE channel). Both can be configured to drive 14 channels (13 passive speakers). Different speakers are active depending on if you're using Dolby processing or DTS: Dolby Surround doesn't support Front Wides, while DTS Neo:X doesn't support rear overhead channels.
A significant difference between the Marantz SR7009 and the Denon X5200W is that the SR7009 has 7.1 multichannel analog inputs, but the X5200W does not.