Plugging Headphones into rear audio port

I have an Aurora R4 and I would like to plug my gaming headset/microphone into my computer. It has an audio input jack (microphone), an audio output jack (game sound) and a USB for power supply. There are microphone, speaker/headphone and USB ports on the front but I would like to plug it into the back of my computer to keep the front ports open for other purposes (I also prefer the cleaner look). There is a microphone input on the back, as well as speaker output (several actually).

When I plug it into the front speaker port it gives me the option to configure it as headphones or speakers however when I plug it into the rear speaker port it only gives me the speaker option. The sound quality is the same as when I plug it into the front audio port and designate it as speakers, but it doesn't allow me to use MaxxSpace (the headphone enhancing option). All of my research has led me to believe that the only difference between speaker and headphone/speaker ports is that the later allows a larger current draw for un-powered headphones, but my headphones have auxiliary power so this isn't an issue.

Any help would be appreciated.

Also what is the difference between the line input and the microphone input?