Flemish & Endless loop are 2 types of strings but can both be made out of string material. either style of string is good and usually in the owners eye for which he prefers. example i can make an endless loop and or a flemish string from dacron B50 material.

Its the material used to make the types of strings that can abuse your limbs.
i read where someone said that endless loop strings had half the strands as the flemish. Not so, you make as many strands as you wish in strings. if you want 24 in a flemish its 12 strands to each bundle in a 2 bundle string. if you want 30 in and endless loop you go 15 full wraps, 15 on each side, 2 sides 30 stands. its the End loops,that will only have 15 strands that will be weaker