One difference you will notice is that the promethean does not have a seperate AUX cable like the Smart Board does for audio/sound, On the promethean much like a TV or External device such as a Blueray player, sound is provided through the HDMI cable. The second connection you should have is a USB this is for the Touch feature of the Promethean, without the USB you will not have touch capability.
When you connect your Promethean to your computer, Windows should recognise it as an Audio output Device, however this may not always happen. This is how to set Promethean as your default output Audio device.
The process for windows 10 and 7 are the same.
1. In the lower right hand corner in the system tray, find the "Speaker" icon.
2. Right Click on the "Speaker" icon and select "Open Sound Settings"
3. When the Sound Panel opens, select Promethean or "Active Panel" and click "Set Default" now when you plug in your Promethean it will default to the promethean.