Female led relationships discussion

Is there a distinct boundary between being a sub and being a slave? I bring this up because, looking at the strict definition of a slave, I question whether anyone here truly fits that label; yet some use ‘slave’ to denote their standing. For those in chastity contexts, it seems to carry another meaning—what is it? I see myself as a sub; however, occasionally I notice aspects of servitude within me, such as being silenced or having my words carefully measured.