PE polyethilene braided lines, Spectra, Dyneema are the most recent innovation in fishing tackle industry. It has 4 times or more pulling strength than mono-filament (nylon and fluorocarbon) in the same diameter, and has very little stretch, about 4%, instead of 20% of mono.
Three improvements are seen for the braided lines, more pulling strength in material, more smoothness as line and overcoming weaknesses.
Bare PE braided lines are very soft, and they have following weakness as fishing line, 1. weak abrasion resistance, 2. backlash on bait casting reels, 3. dig-in at spool, 4. light weiht ratio, 5. weak tie strength.
I categorize braided lines into 3, soft body braids, medium body hybrid braids and hard body braids. Soft braids are lines for the best pulling stregth. They have some suaface coatings to add some abrasion resistance, but basically these lines should be used without contacting to anything. Tying mono-filament top shot is always necessary. The hybrid braids are to overcome some of the weaknesses by braiding mono-filament to the PE braids. Hard braids have hard resin coatings on their surface are to overcome as many weaknesses as possible, and to make them to be used with bait casting reels. Fireline is in this category.