What's the dif "sync only checked songs and videos"&"manually manage music

Niel wrote:
The first option automatically synces the iTunes content which is checked. The second option only transfers content manually dragged to the device.

(54740)

Okay , I had "*Manually Managed*" checked in the summery and had restored the iPod to get rid of some videos that wouldn't go away. When I went to Music and checked *Sync Music* Selected Playlists, etc. it appears that the *Manually Manage* box in the Summery un-checked itself.
Interesting,
So just to clarify ; When *Manually Managed* is checked you can only drag things into the device from your library (outside the device), using the Music tab within the device will negate this ?

Thanks All
The first one to give a good link to an in-depth description of this issue gets the solved star 😉
--bob

Thanks Diane