AWOS & ASOS - what's the difference?
 

Does anyone know? I've read the blurb in the AIM and they seem the same to me.

?????

The only difference that I know of is ASOS is run by the FAA, AWOS is run by the local airport authority.

isn't one or the other suitable for inclusion on weather charts ?

Here's gouge straight from the FAA:
11. Are all AWOSs and ASOSs identical?
No. Although similar, there are several versions of AWOS with different arrays of sensors. The report format is similar and is controlled by international standards. Reports differ by the type of sensors on the system (system configuration). A01 indicates an automated station without a precipitation identification sensor. A02 indicates an automated station with a precipitation identification sensor.
An AWOS I processes and outputs temperature, dewpoint, barometric pressure, density altitude, wind speed, wind direction, and gusts. An AWOS II adds visibility to the AWOS I parameters. An AWOS III provides cloud height/condition in addition to the above parameters. An AWOSIII-P adds a precipitation type identification sensor.
An ASOS includes the parameters of an AWOS III plus a freezing rain sensor and thunderstorm reporting.
12. What are the differences between federal and non-federal AWOS stations?
The primary difference between federal and non-federal AWOSs is that the federal AWOSs are FAA owned and maintained while the non-federal AWOSs are state or locally owned and maintained. The federal AWOSs also have thunderstorm reporting capability through the FAA’s Automated Lightning Detection and Reporting System (ALDARS).