@Pikarus I do see what you mean, but they seem different in the way the flame trails look, but yeah from afar they look the same, but the ones on that set you pointed out have more branches off the original fire ball.
Both the sets are brushes...both these brushes are from the same pack & are similar...I don't think he really tried to copy someone else's texture set....There are a decent no of flame sets around and most of them would have the same brush pack
btw the torso is bit too dark compared to the legs..