The difference between polar powermeter and Power Tap

Someone asks what difference between Polar powermeter and PowerTap?
You can find the difference from the pictures below. Just do it by yourself!

BIKE : CERVELO S3
WHEEL: PowerTap Wheel
Duration 1:00:00
Energy Expenditure 609 kcal
Average Heart Rate 143 bpm
Maximum Heart Rate 162 bpm
Standard Deviation 13.7 bpm

Minimum Speed 10.3 km/h
Average Speed 41.4 km/h
Maximum Speed 56.0 km/h
Distance 39.5 km
Odometer 1095 km

Minimum Cadence 52 rpm
Average Cadence 93 rpm
Maximum Cadence 117 rpm

Polar Powermeter:
Minimum Power 107 Watts
Average Power 239 Watts
Maximum Power 468 Watts

PowerTap :
Minimum Power 0 Watts
Average Power 154 Watts
Maximum Power 282 Watts