Curative, sanative, restorative, remedial, corrective are comparable when they mean returning or tending to return to a state of normalcy or health.
Curative is applicable to whatever effects or, sometimes, seeks or tends to effect a complete recovery especially from disease of body or of mind.
Sanative is a general term applicable to whatever is conducive either to the restoration of or the maintenance of health, whether of body and mind or of spirit or morals; the term often comes close to salutary in meaning.
Restorative is occasionally applicable to what restores to health but more often to what revives someone unconscious or renews or refreshes someone or something overstrained or exhausted.
Remedial is much the broadest term of this group and like the related noun (see REMEDY n) and verb (see CURE vb) is applicable not only to whatever alleviates or cures disease or injury of body or mind but to whatever tends to relieve or correct a faulty or evil condition (as of the community, the law, or the body politic).
Corrective (compare CORRECTIVE n) in many of its uses comes close to remedial, but, unlike the latter, it cannot ordinarily replace curative; specifically it applies to what is designed to restore something to a norm or standard or bring it up (or down) to a desirable level from which it has deviated.
In this relation the term is peculiarly applicable to material objects that supplement or compensate for a defective function or part, but it may be used interchangeably with remedial in most contexts, though the emphasis may be more on making good a defect or deficiency than (as in remedial) on relieving the distress it causes; thus, one would speak of corrective (rather than remedial) shoes for the relief of weak ankles, but one could say that among remedial (or corrective) measures for weak ankles are shoes with special lifts in the soles.