Child Objects return a collection of objects of a specific type (object class) in a GUI. For instance, you could retrieve a collection of all of the webedits, buttons, WinEdit, checkboxes, etc. One common way to do this is using a description object. Here's an example of getting all of the WebButton objects on a page:

set obnDesc = Description.Create()
obnDesc(''Class Name'').Value = ''WebButton''
Browser(''title:=.*'').Page(''title:=.*'').ChildObjects(''objDesc'')

Child items are used when dealing with a WebTable object. You can access the cells in a WebTable as ChildItems.