HP 410A vs 410X: same Color LaserJet toner family, same printers. The difference is page yield (and cost per page).
410A is the standard-yield set. Each cartridge in the CF410A–CF413A pack is about 2,300 pages (black, cyan, yellow, magenta). Buy 410A when you print lightly, or you only need one color.
410X is the high-yield set for the same machines: black (CF410X) about 6,500 pages; cyan / yellow / magenta (CF411X / CF412X / CF413X) about 5,000 each. Fewer swaps. Better cost per page if the printer runs often.
Printers on both: Color LaserJet Pro M452dn / M452dw / M452nw, MFP M377dw, MFP M477fdn / M477fdw / M477fnw. Not 414A/414X (M454 / M479). Not 218A/218X.
We sell a compatible 410A 4-pack (CF410A set) and a compatible 410X 4-pack (high yield), chips installed. Singles are on the store if you only need one color.
When to buy which: replace toner more than a couple of times a year → start with 410X. Occasional color jobs → 410A is enough. If the label on the cartridge in the printer says 410X, stay on X unless you intentionally want fewer pages per cartridge.