Comes up constantly, so here's the short version from someone who runs both.
Diode (445–455nm), e.g. LP2/LP4 diode module:
- Wood, leather, cardstock, dark acrylic, coated/painted metal, slate, glass with a coating.
- Cuts thin materials. Cheap, small spot, easy.
- Will not mark bare metal usefully, and cannot see clear acrylic at all.
Fiber (1064nm), e.g. LP3, LP5 fiber module:
- Bare metal: stainless, aluminium, brass, titanium. Deep engraving, annealing colours, black marking on steel.
- Marks some plastics beautifully (ABS, some nylons) and ignores others entirely.
- Does not cut wood and does almost nothing to organic materials — it reflects or passes straight through.
Practical upshot: if your work is wood/leather/acrylic, a diode is the right machine and a fiber would be a mistake. If you're marking tools, tags and metal parts, fiber is not optional — no amount of power on a diode gets you a durable mark on bare stainless.
Safety, because it's different: 1064nm is invisible and your blink reflex does nothing. Diode glasses do not protect you. You need OD5+ rated at 1064nm, and enclosed operation whenever practical. Fiber reflections off a shiny part go where they like.
Dual-source machines (LP4, LP5) exist because these two jobs genuinely need different light.
