Based off a comment here, some quick definitions for you as they’re used in the Eldraeverse:
(Note, of course, that I’m using a considerable amount of Minovsky cognitive science here; your mileage may vary if you try and apply any of it elsewhere.)
sentience: the property of having sense perception; the capability of experiencing sensation, without necessarily associating mental symbology with sensation. Includes not only sophonts, but animals, plants, single-celled organisms, and a variety of simple devices (even something as simple as a thermostat can reasonably be described as sentient, if minimally so). Quantized, for technical purposes, as sensory bandwidth in bits per unit time.
sapience: the capacity for rational thought and creativity; not necessarily associated with either sentience or volition. Again, includes many non-sophonts, primarily animals, but also various types of computer program.
autosentience: self-perception and self-reflection, metacognition; self-awareness (“I-ness”); the possession of qualia (mental symbology associated with sensation), which for the purposes of Eldraeverse cogsci is a corollary of metacognition. Most animals (but not the plants, single-celled organisms – this is from an Earth perspective, and such odd plantimal life forms as the mezuar and the selyéva aren’t counted among these plants – and devices) qualify as autosentient to some degree, as does thinker-grade or above AI software (although not simple AI expert systems, which are sapient but not autosentient; they have no qualia, merely data).
In civilized societies, certain civil rights are associated with autosentience, principally concerned with the right not to be subjected to arbitrary suffering since, with autosentience, one attains the ability to experience suffering.
threshold autosentience: the minimal degree of autosentience required to meaningfully describe oneself as “I”; the possession of a meaningful self-associated self-symbol in one’s mental architecture. (In many sentients, it is associated with the presence of a consciousness loop organizing cognitive processing into a narrative thread, but this isn’t a requisite of these mental architectures; the case of non self-associated self-symbols is odd, but does seem to be permitted – see Stross, here, although this isn’t the path their AI development took.) It is often, but is not necessarily associated with a high level of sapience; many animals qualify as sapients without possessing threshold autosentience, and obviously many programs, including much alife, possess very impressive problem-solving abilities while being entirely devoid of autosentience. Thinker-grade AI possesses this, too, but does not have volition.
volition: the capacity for nondeterministic choice; in sophonts, associated with possession of one of a class of nondeterministic algorithms known as logoi. (However, known/constructable sophont mental architectures utilize primarily deterministic choice with only occasional logotic input.)
sophonce: possessing all of threshold autosentience, sapience, and volition; i.e., being “a self-aware, self-defining entity capable of independent reason and volition”. Biological sophonts and digisapiences, the highest grade of AI entity.
Have all the natural rights of people, because they’re the definition of “people”.
pro-sophonce: the almost-but-not-quites, the creatures almost reaching the requirements for sapience/threshold autosentience to be counted among the sophonts, but not quite. The dolphins, dogs, octopi, (on Earth) apes, etc. Again, generally receive some civil rights in civilized societies due to this status (and, by the same metric, generally considered prime candidates for uplift work), but not considered actual people unless uplifted.