DHT_Driver DHT11 versus DHT22 inconsistent readings

[hrpunio]

I test DHT22 and DHT11 side-by-side (common Vdd/Gnd/Null) Data connected to pins 24 and 25.
The figures generated by DHT22 seems reliable as well as temperature in case of DHT11.
The problem is with humidity as reported by DHT11 sensor
which is circa 20% below expected/reported by DHT-22 value (for example 56% versus 38%). Cannot explain this phenomenon:-)

[ladyada]

DHT11 is not as good a sensor - this is not a software issue