Brass: supplied with the printer, valid for printing the most common materials (PLA, PETG, ABS, ETC). They have better thermal conductivity than steel nozzles
Stainless steel: suitable for printing objects that will be in contact with food or with the mouth or respiratory tract since it does not contain lead.
Hardened steel: suitable for printing with materials that contain chips from hard materials such as carbon fiber, metal, etc. Their lifespan with these materials will be longer than a standard brass nozzle.
Silver-plated copper: valid for printing at high temperatures (<500 degrees) on non-abrasive materials
Nozzle X: the most professional E3D nozzle, hardened steel coated with nickel and coated with a special WS2 coating, they allow printing of up to 500 degrees of abrasive materials.
<0.4mm: suitable for maximum detail at the expense of increased printing times
0.4mm: most common size, with a good compromise between printing time and detail
0.5-0.6mm: nozzles commonly used to increase printing speed without a great loss of detail, also used for materials with large traces such as wood filament.
>0.6mm: used for large prints, the loss of detail is notable. For these sizes, it is recommended to have a volcano-type hotend, since the amount of material to be melted per second can be too much for a normal hotend
For materials that contain traces of hard materials such as metals, carbon fiber, etc., the use of hardened steel nozzles is recommended.