Sefirah and Partzuf: Government — overall and detailed.
A Sefirah is one of the ten powers (the foundation). A Partzuf is the same power fully articulated as a Likeness of Man with 613 parts. Cordovero reads via Sefirot; the Arizal via Partzufim; both are valid.
Op. 17 closes the Fundamentals unit by drawing the most consequential terminological distinction in Klach. The book's vocabulary will use Sefirah and Partzuf in carefully distinct ways from here on. Op. 17 is where those distinct uses are formalised.
A Sefirah is one of the ten overall powers — the general form of an attribute of His Will. The Sefirot, in this overall sense, are the underlying powers on which everything is built. Cordovero's Pardes Rimonim reads the entire cosmic government in terms of the ten Sefirot.
A Partzuf (which means "face" or "configuration") is a Sefirah seen in detail — the same power articulated in the form of a Likeness of Man, with 613 parts, ordered along three columns (Kindness, Judgment, Mercy). The Arizal's Etz Chayim reads the cosmic government in terms of Partzufim. Where the Sefirah is general, the Partzuf is operational.
There is no Partzuf without a Sefirah. Every Partzuf is a Sefirah seen in operational detail. The two readings — Cordovero's and the Arizal's — are not rivals; they are two pathways to the same government. The Sefirah-language is foundational; the Partzuf-language is operational. Klach uses both, foregrounding one or the other depending on what the present argument requires.
This division of labour governs the entire second half of the book. Sefirah names the underlying simple-light power; Partzuf names the fully-articulated operational anatomy. By Op. 71, the division will be settled formally: the Sefirah is the simple light; the differentiation into particulars belongs to the Partzuf.