You can tell the difference between bikes in terms of ride but a lot of factors go into that ride and it's a question of understanding how it all might work together. For instance I have a cromo mtn bike, retired to touring and day rides. It's a lovely smooth bike but it rides harshly over sharp bumps with the current tyres on it, lowering the pressure eases it a little but the tyres are just a bit stiff and rigid even so. My alu mtn bike feels great as well but it has 2.3inch tyres but the back end is stiff compared to my steel mtn bike. My road bike is steel and just all round very comfortable, especially now I have the pressures nailed. Before I bought it, I rejected a number of bikes because I didn't like the ride, same with my steel mtn bike. It's all very subjective and, as I always do, I recommend you ride anything you are thinking of buying.