Multi-colour tells you the mechanism, which decides waste and speed: Toolchanger (Prusa XL, Snapmaker U1) and Dual nozzle (H2D, IDEX) switch heads with no purge; Multi-spool + purge (Bambu AMS, Creality CFS, Anycubic ACE, Qidi Box) and MMU (Prusa MMU3) feed one nozzle and purge each change — expect a poop-bucket and 2–4× print time on colour-heavy models. Max colours is with the largest first-party setup.
Hotend / extruder — direct drive handles TPU and fast retractions; Bowden is lighter but fussier. Nozzle max °C gates materials (300 °C+ for PA / PC / CF blends); the nozzle-change note says whether it's a quick-swap module or a wrench job.
Enclosure matters for ABS / ASA / PA; a heated chamber (H2D, Core One, X1E, Qidi Plus 4) is the step above for warp-free engineering plastics.
Cloud — LAN-only OK means the printer runs without the vendor cloud. Bambu's Jan-2025 firmware change put third-party slicer control behind Bambu Connect unless you enable Developer / LAN mode; Prusa, Klipper machines and kits are fully local.
Belt / infinite-Z printers (Creality CR-30, iFactory3D One Pro, BLACKBELT) have a conveyor for the bed and a 45° gantry, so one dimension is unbounded — they print a part of any length, or run the same part back-to-back unattended. Build volume shows the fixed cross-section; no L or $/L. Filter above.
$ / L under build volume is price per litre of print space — the honest big-printer comparison.