Just as Nietzsche identifies activity with will to power, Spinoza identifies it with the conatus, the striving for self-preservation and increase in power. The conatus must be understood not as a possession of an individual but rather as its very definition, its actual expression. It is what defines a grouping of parts as a single coherent individual, a single unified drive, rather than as a multiplicity. It individuates an actor as a coherent whole. Insofar as that common drive is maintained, it makes sense to speak of a single mode, one which strives toward certain ends, which has a mind, and which engages in actions (or is subdued in its attempts to act). Though such a mode is never free from the causal chain of nature, it nevertheless can be understood as acting for itself, and ‘in its action the nature of the thing appears in its complete plenitude of power [ganzen Machtvollkommenheit], so far as it extends.’ Hence an ontology of nature as activity does not preclude making sense of individual actors with specific differences, as Bittner asserts it must. I believe this to be, mutatis mutandis, very close to what Nietzsche is trying to express in GM I.13. To define a thing by its action does not eliminate the possibility of speaking of a thing as such. A unified will to power can itself individuate, and, even if properly understood as action rather than as substance, still allow us to speak of an enduring identity through time. Because wills can manifest themselves in so many alternative ways, human diversity can be accounted for, and it is even possible to speak to some degree of types.
David Wollenberg, “Nietzsche, Spinoza, and the Moral Affects” in Journal of the History of Philosophy 51.4: (2013), pg. 632-33