This topic my be the more confusing than any other.
Define copolymer fishing line? What is a hybrid fishing line? What is mono line? How do they differ?
1. Copolymer line is a blend of 2 polymers, they are mixed during the pellet melt cycle when extruding the line into 1 filament.
2. Hybrid line is 2 polymers,1 Nylon and 1 fluorocarbon that are co extruded. The nylon polymer is the core and the fluorocarbon is extruded over the nylon becoming the outer surface of the single filament line.
3. Mono has become the term for single filament Nylon polymer line.
4. All of the above single filament lines are monofilament or single filament strand of fishing line, they appear or look the same. How do they differ? Fluorocarbon is heavier than Nylon and less flexible, it's not stronger or doesn't have higher physical strength, therefore it stretches equally to Nylon. Nylon absorbs water, fluorocarbon doesn't. Nylon being lighter weight tends to float on top of the water, fluorocarbon sinks.
Fluorocarbon is claimed to be less visible to fish do to lower refraction of light...who knows how fish see line or care? Single filament line that measures the same diameter have nearly equal strength, that includes all of the above; mono, copolymer and fluorocarbon and they all stretch equally. The primary difference being coefficient of drag going through water, fluorocarbon has less than Nylon and fluorocarbon sinks where Nylon tends to float. The downside of fluorocarbon is it's less flexible and tends to break if bent or notched (low notch strength) resulting in lower knot strength. Copolymer single filament line offers blended additives to help increase strength (questionable), self lubricate, improve heat resistance and UV resistance compared to a single polymer Nylon line. Hybrid single filament line claims to be less visible like fluorocarbon with a fluorocarbon jacket and remain flexible with good knot strength like Nylon. Hybrid sinks slower than fluorocarbon, stretches and is the same strength as Nylon or "mono" line.
Beware that line manufacturers have learned to increase the line diameter and label the larger diameter (thicker) with lower pound test rating. Evaluate all single filament line by it's diameter, do not be fooled by (thick line) with larger diameters, unless that doesn't matter to you.
Bottom line; no difference between "mono", copolymer and hybrid single filament fishing line, fluorocarbon offers less drag coefficient, heavier and sinks with less knot strength. No panacea in fishing line.
Tom