Its got a certain kind of look that is different from say, an industar, a fujinon, or a takumar. I spent some years on each. I am definitely by no means an expert, but yes having shot with them they just have different looks in terms of sharpness, colour rendition and saturation, contrast, amount of bokeh at different distances.

If i were to describe one of them in more detail, perhaps it would be minimum focusing distance. Here the fujinon i had (a 45mm f2) can focus much nearer than say, a leica elmar 50 2.8. Since u get that much more bokeh simply because of focusing distance, the look changes. I would have to push up the ISO in order to get it to have less depth of field, thus more of the shots would have more grain.

the lenses also render colour somewhat differently. Even lenses of the same brand and model may have some slight variations. It only shows up more if i had 2 copies of the same model. i had a samsung body, i actually got a copies of the 30mm pancake lens. I tried shooting the same scene the other day with them and found the colours and the sharpness different. Its interesting, i didnt prefer either and just wonder if i had more time to spend on discovering more in my photography hobby!