This comparison is quite simple, given how much this pair has in common with one another.
Hartley Rathaway and Isaac Bowin were the sons of affluent parents. Each possessed musical talent and a greedy heart. Each were disadvantages, Hartley by his early-childhood deafness (eventually cured thanks to his father's money poured into research on his condition) and Isaac by his young manhood's inclination towards crime (finding himself in an Indian prison accompanied by his instrumental instructor).
Hartley developed a pipe and became Earth-One's Pied Piper, while Isaac created a fiddle and debuted as Earth-Two's Fiddler. With the mesmerizing abilities generated by their devices, they were able to control the actions of others, yet each repeatedly faced their own Flash and continual defeat. Even when they joined teams, the Piper's Rogues Gallery and Fiddler's Injustice Society, it always ended for them on a sour note.