I don't know why I am even justifying your existence with an answer, but if it will shut you up I'll go for it.
The volume differences in the enclosures you linked to result in different frequency responses of the subwoofer system. Nothing more, nothing less.
The effect of box volume on a ported system is much the same as for a sealed enclosure, small boxes raise the Q and increase boominess more than do large boxes. This indicates a large box should be used for speakers with a high Q and a small box should be used for speakers with higher damping and a lower Q. What is Q you ask? It is a numerical term used to measure the degree of damping on a speaker. It stands for resonance magnification, the tendency of the speaker to peak in response at the resonant frequency. The greater the damping on a speaker, the lower its output at resonance and the lower its Q. When drivers are put in a closed box, the Q and the resonant frequency will both be raised.
Generally speaking, the Q of the driver in the enclosure should be between .7 and 1.0 and this will result in a gentle roll-off in the lower frequencies. A Q higher than 1.0 will seem boomy with unpleasant peaks in the frequency response.
So, to get this back into terms of your question, the lower tuning frequency of the smaller enclosure is there to offset the higher Q and higher resonant frequency the smaller enclosure caused. The larger enclosure has a higher tuning frequency because the Q and resonant frequency did not rise as much. Also note that although the enclosures all say they will work with either the L5 or L7, the response will be different for each because the L7 has a higher Q (.51) than the L5 (.47). (Speakers with a Q of 0.38 or lower are typically considered to have a low Q.) This means the L7 will have more boominess, or an exagerated peak at its resonant frequency than the L5 if each is put into the same enclosure. This of course is undesirable if you want a smooth, musical subwoofer but very desireable if you are striving for a one-note wonder for SPL comps that sounds like ass with music.
Notice I have said nothing about which one would be louder. Both sizes can be louder than the other depending on the tuning of the port, but the smaller enclosure has the better capability to have more "boominess" because of the higher possible Q.
There are many more aspects of speaker design that will impact the performance of a subwoofer system than the small amount of information I have included here. The Thiele-Small specs for the driver are used to determine what the enclosure specs need to be to achieve a desired result, or they can be used to estimate what the result will be based on the enclosure that is available.
Convinced yet that a subwoofer in a larger box is not louder just because it is in a larger box? That there is a lot more to the physics involved?