I have two steel bikes of similar size, design and intent (Marinoni Sport Tourer and Rivendell Rambouillet), equally well constructed, very similarly equipped with nearly identical gearing, similar overall weight, and very similar fit. Even under my modest efforts, the Marinoni clearly and always feels more responsive than the Rambouillet. It conveys a feeling that encourages me to pedal a little harder, shift up to a bigger gear, and push myself. The Rambouillet is very solid, but just doesn't give that feedback.

I've swapped wheels and tires between bikes, and that doesn't change the inherent differences in feel. And FWIW, the Rambouillet is made from oversize Kaisei tubing and the Marinoni is standard size Columbus SLX tubes, so the former is probably stiffer. Also notable is that on my 37-mile round trip bike commute, both bikes tend to result in the same average speed over that distance. What makes a speed difference over the entire distance is my motivation (am I running late?), the wind, and how tired or not I'm feeling that day so am I willing to push that bigger gear longer. But for fun, the Marinoni is always my preferred ride.