No.1 is hot rolled, annealed and pickled: dull, slightly rough, used for tanks, structural work and anything that will be painted, clad or left industrial. 2B is cold rolled, annealed, pickled and skin-passed: smooth, semi-bright, the most common finish for general fabrication. 2D is the same without the skin pass, softer and duller, for deep drawing.
BA (bright annealed) is cold rolled and annealed in a protective atmosphere so the surface stays bright and reflective, used for appliances and decorative trim. No.4 is a brushed finish with a 150 to 180 grit grain for kitchens, lifts and architecture. HL (hairline) has longer, finer continuous lines. No.8 is mirror polished.
Finish affects price, lead time and what you can do next: a No.1 plate cannot be polished economically to No.8; a 2B plate can be brushed or polished; a BA plate is ready for coating. Always state the finish and whether PVC protective film is required.