A submissive agree his limits and practices with me. Logically, if they don’t interest me or not agree on these points, the relationship has no future, because if I demand more than he can give of himself or if I get bored, it’s better to clarify from the start to prevent to waste our time.
A slave has no limits, abide by mine. The slave does not think in terms of submission but property, does not make decisions, is more inclined to perform uncomfortable tasks weather they are repetitive or unpleasant. Does not expect to be consulted, accepts my decisions. No raises to end the relationship but may do so at any time, he surrenders as a property with no more rights than those I want to grant him.
The submissive, either by personal circumstances or by choice, saves plots for himself but on the terms agreed is given to me completely. I can force some limits and other are immovable.
These are only some of the differences between them, but even there are, it doesn’t mean one is better than the other, just different.
And in many cases a submissive surrends as a slave, although this requires a large mutual understanding is achieved over time.