Coach, the way to tell is to put the stethoscope you use for checking vibrations and noises down on the transmission and determine if there is a thumping noise.
OK, OK just making sure you're paying attention. I copy and pasted this from another site.
There is a lot of confusion about what a Live PTO is and isn't. A live PTO, normally, has a 2 stage clutch. You can depress the clutch 1/2 way in and the transmission will stop but the PTO will continue to spin. If you depress the clutch all the way the PTO will stop also. This is very useful when mowing because you can stop, change gears, back up, etc while the mower continues to receive power.
If the PTO is not "live" it will stop receiving power every time the clutch pedal is depressed. Because the PTO is always directly connected to the transmission you will need an over run clutch if you use a high momentum implement like a mower.