Horses for courses. The two types of pads are meant for different conditions. Resin pads work well from cold and at lower operating temperatures. They bite quickly and consistently when used at low speeds. Sintered metal pads on the other hand are intended for high-performance riding. They bite at much higher temperatures and perform best when braking hard and consistently. They do last longer in gritty, wet conditions but that's not their primary application. Although it is difficult to box riding styles, think of sintered pads for hard-core endurance/freestyle and downhill riders and resin (also called organic) pads for city riding.
Not all discs are compatible with both types of pads. Resin pads, due to their lower operating temperatures, are generally used on cheaper discs which haven't been heat treated and not made from heat-treatable stainless steel. Sintered pads will quickly destroy them. Sintered pads only work on special discs. The disc's intended utility is usually indicated on the disc but if not, sintered pad discs are recognisable in that they are not stamped out but laser cut to shape.
Further, you cannot just swap nilly-willy between this pad and that pad. Brake pad material transfers (and have to) onto the disc and when putting sintered pads (or vice versa) on a disc that previously had resin pads, is looking for trouble. The result will be noise and poor performance.
There is no commercially available chemical that can de-contaminate a disc from pad residue. Only abrasion can save a disc and prepare it for a different type of pad. No matter what the bottle says, it cannot clear a disc.
Resin pads are the least difficult to live with. They are quiet, brake predictably and quickly. Sintered pads have to warm up before biting hard, leaving them slightly unsatisfying for normal pottering along. Sintered pads are made from metal filings compressed at a temperature that's just-just below the metal's melting temperature. Their grain structure is biscuit like. Resin pads on the other hand are cast from liquid and then cured. The grain structure is glass-like. Both types of pads can be impregnated with fibres such as ceramic, aramid (Kevlar) or asbestos.
