The slave vs sub semantic battle will likely remain one of those great unresolved issues of Lifestyle verbiage for me. As MMI most recently pointed out, even one that is labeled a slave is a slave by consent and with the power to rescind their commitment at any time.
Granted, it may take an extreme act for them to do so, but they still have that power regardless.
So, how do you really define a Lifestyle slave then? For me it's like trying to pin down what it takes to be an artist - as my friend L (who is a painter) is fond of repeating, "Amber, the only criteria required to be an artist is to posses the ability to say, 'I am an artist.' It's one of the only jobs where no one can actually prove you otherwise."
And please, before the irrational flaming begins because someone's blood sugar is low today, no, I do not think all or even most Lifestyle slaves just decided to announce that they are what they are because they thought it sounded sexier than being just a "plain ol' sub." Those I have met that bear the title tend to be extremely devoted to all aspects of their service and are frankly some wonderful girls (sorry guys, I don't really know any male slaves well).
As for the "which is better?" or "deserves more respect?" debate between subs and slaves that these threads inevitably seem to fan the flames of; how about instead of judging people by how they choose to represent their submission or how often, we give them credit for how well they apply themselves to the role they have individually taken on? What's better about a slave that shirks her contracted obligations than a sub that gives 110% of herself each time she sees her Dom, even if it may only be once every couple of months?
A lot of folks think that to be a doctor, for example, is to have a career that deserves instant respect and a higher level of social regard as opposed to say, being a mechanic. However, if I'm given the choice between a lax doctor and a dedicated mechanic, guess which one is going to have my respect? Too many variables folks, sorry, no one role gets any instant admiration from this girl. Simply, whatever you choose just do your best to be your best at it.