Split type — Fully separate = two independent halves you place anywhere; Unibody split = one piece with a fixed angled gap (Kinesis Advantage, MD600); Adjustable bridge = halves on an articulating mount (Naya).
Layout — Column-stagger (ortho columns offset per finger length) is the ergonomic-keyboard norm; Row-stagger keeps a normal typewriter grid, gentler relearn (Keychron Q11, MD770).
Firmware — QMK / VIA / Vial / ZMK are open and fully remappable; Oryx and Bazecor are vendor GUIs on top of QMK; a few are closed.
Assembly — Prebuilt ships ready; kit ranges from solderless hot-swap to full soldering; PCB / files only means you source parts yourself. Kit prices in the Price column are the base kit — expand a row for what's included.
Kit prices are not apples-to-apples (bare PCB pair vs full solderless kit vs vendor-assembled). Don't sort on price naively.