Collaborative Building

Allow anyone to move (Edit window, General tab)

Collaboration this allows:

Allows someone to rearrange your stuff.

Collaboration this does not allow:

Does not allow modifying the object itself (shape, color, etc.) nor modifying the contents.

Protection this affords

Only the objects your choose can be modified.

Drawbacks

You need to remember to turn this off or strangers can move your stuff.

Friends - Can modify my objects

Collaboration this allows:

This gives your friend the ability to modify your objects.

Collaboration this does not allow:

Your friend cannot change the next owner permissions. Only the owner can do that.
Your friend cannot change the contents of your objects, However, your friend can take the object, then rez it again, and can then modify items in the contents(if the next owner permissions were set).

Scenarios best suited by this

Building objects or buildings that do not require scripts or other items in contents.

Protection this affords

The other user cannot modify scripts in your object.. most of the time. If next owner permissions are permissive, the friend can take and rez and then owns modifiable copies of the script.

Drawbacks

Your friend cannot help you fix your script.
Your friend can modify any of your items, and delete your content.

Groups - Object Management - Manipulate (move, copy, modify) group-owned objects

Collaboration this allows:

This allows someone to modify a script in your objects if the script is set to "share with group".

Collaboration this does not allow:

none?

Scenarios best suited by this

Large collaborative builds.

Protection this affords

Only the people with the Manipulate abiliity can modify items.

Drawbacks

Turning on the "share with group" flag for each box, script, notecard is tedious.