While concrete may be a harder surface than asphalt, other than preconceived perceptions, there is not an appreciable difference in deflection (Force returned from a surface) between concrete and asphalt.
There is a difference between grass, dirt, rubberized track surfaces, etc., but between asphalt and concrete any difference that you perceive is perception only, and not real. You simply don't generate the PSI force necessary to make a difference.
There have also been studies where the forces of various surfaces were compared with running strides as shown by the following links
Study comparing rubber, grass, concrete and asphalt
Forty-seven adult recreational runners ran twice for 40 m on all four different surfaces at 12 ± 5% km · h(-1). Peak pressure, pressure-time integral, and contact time were recorded by Pedar X insoles. Asphalt and concrete were similar for all plantar variables and pressure zones
Study comparing ground reaction forces
No significant differences were detected among the surfaces for shoe reaction forces, contact time, or impulse (P > 0.05). This implies that runners who choose to run on stiffer surfaces are not exposing themselves to additional risk as a result of loading but possibly because of internal compensatory mechanisms. However, these results may not apply to all runners.
This last one does indicate that there may be a difference in how people run on various surfaces, but the surfaces themselves are largely irrelevant.