Both the submissive and the slave are females, so both are submissive to various degrees. They are both animals, after all they are not minerals or plants.
But what are some of the differences between the submissive and the slave. A submissive is free while a slave is not. Part of being free is being free to make decisions for oneself. Part of that is deciding how to dress, act, behave, and what to think. Being free is having the ability to control your own life. A slave lacks both these things.
This is not to say children are free nor are they slaves. Children as they get older are able to make more and more decisions for themselves, submitting to their parents, until such time as they become independant from their parents. Thus children are a special case and are neither free nor slaves, they are children. The only reason why children are mentioned is because they come into contact with free people and slaves in their everyday lives. Beyond this contact children have no place in this discussion thus are not going to be discussed further accordingly due to their special status.
Thus the main difference between a submissive female and a slave is control. One could also say ownership is also a key component between a submissive female and a slave.
Control and ownership go hand in hand. After all how can someone own something if they have no control over it. But someone can control something and not necessarily own it. Thus another element must be present to differentiate between just a submissive and a slave. And that is being subject to another's will.
So in order to be a slave one must be owned, controlled, and subject to another's will. If all these make up a slave then why is it that slaves do not show proper respect towards masters and mistresses in general. I read ton of profiles where people claim to be slaves yet set limitations and/or conditions to their slavery. They also make demands upon potential owners.
This is not to say that a slave should not pick their owner with care. Since we live with concentual slavery and not true slavery the slave does have a choice until they become owned if they are a true slave to determine who will own them. But this does not give them the right to be rude in the process. The only people who have the right to be rude is free people due to their status of being above a slave.
Thus rudeness from slaves come from either not truely being slaves or from the lack of knowledge of protocols on their part. Whether a master owns the particular slave or not, a slave should be subject to the proper protocols. And if the slave is owned then the slave should be definately subject to protocols appropriate for the slave.
Masters that do not enforce protocols onto their slaves show a lack of respect for other masters and mistresses. And if a master does not show proper respect for other masters and mistresses then how can their slave follow suit and thus be a slave in depth beyond their commitment to their owner.