That's not a difference in degree at all. It's a difference in kind, and the distinction isn't even close.
I feel that you have let me down somewhat with your previous explanation of the difference between the employee and the slave, because it is clear then that you do not at all abide by the difference you set out. It is not, after all, the employee's ability to pursue his own self-interest that makes him free rather than a slave.
Actually, yes it is. I'm sorry you feel let down, but your side of this discussion is frankly indefensible.
I think that when you introduce the supplemental notion of the qualitative difference, you take some steps back from a stock libertarian talking point that you might or might not have intended to support. At least, a proper response would require some elaboration of the notion of employee liberty.
I can sympathize if you don't have time or energy for that, and I'm happy to let the matter rest inconclusively. For what its worth, I'd actually be rather interested in whatever ideas you developed to articulate your position, as they would be a more useful reference point than I currently possess the next time I encounter someone making a reference to employee liberty I feel deserves to be tested.