The actual difference
Conditioner and mask do the same category of job — deposit conditioning agents that smooth the cuticle, add slip and reduce combing friction. Where they differ is concentration and intended contact time.
A conditioner is formulated for one to two minutes and to be used every wash. It is optimized for detangling and everyday smoothness, and it is deliberately light enough that daily use does not build up.
A mask is more concentrated, with a higher load of emollients and often heavier ones, formulated for five to fifteen minutes and weekly use. That concentration is why it is not simply conditioner with more patience — leaving conditioner on for twenty minutes gets you a slightly better conditioner, not a mask.
Do you need both?
Yes, if your hair is coarse, curly, high porosity, color-treated or bleached. Those all mean hair that loses moisture faster than the everyday step can replace, and a weekly mask is the highest-value single addition to the routine.
No, if your hair is fine, straight and untreated. A good conditioner used properly is enough, and a weekly mask on fine hair usually produces limp hair and the conclusion that masks do not work. If that is you, spend the money on a light leave-in instead, which will do more.
Sometimes if your hair is fine but damaged — in which case use a mask on the ends only, or use a leave-in treatment format where you control the dose.
Two things that are widely repeated and not true
"Leave the mask on overnight for better results." Most of the effect lands in the first five to ten minutes. Beyond that you are mainly conditioning your pillowcase. With a protein-leaning mask, overnight is actively counterproductive — that is how hair ends up stiff and brittle.
"A mask replaces conditioner." On mask day it does. The rest of the week you still want the everyday slip that makes detangling safe, and hair is at its most fragile when wet (AAD, everyday hair care).
The other thing worth knowing: if your mask has stopped seeming to do anything, the likely cause is buildup rather than the mask. Porous hair grabs everything, and after a few months the strand is coated and nothing new reaches it. One clarifying wash usually brings the mask back to life — the clarifying shortlist is here.
We have not used these products ourselves. They are chosen from what is in the formula, what those ingredients are documented to do, and whether that matches the problem this page is about — and every product below links to the manufacturer's own page so you can check the formulation claims yourself. The full method is here.
How we picked
Products we have personally tested: none
Most hair care roundups are written in a "we tested these" voice. We have not, and saying so is the point. These picks are chosen the way an informed shopper would choose them: read what is actually in the formula, check what those ingredients are documented to do, match that against the specific problem the page is about, and confirm the product is still being sold.
Each pick gets a role — the drugstore option, the one for high porosity, the gentlest of the set — rather than a score out of ten, because a score would imply a measurement nobody took. Nobody pays for inclusion or placement, and when the cheap product is the right answer we say that too. The full method is on one page.