FYI
In both cases you are asking to get the content of the field. In the list it returns a list of titles, remember it processes one at a time and warps each as a title..
It does look a little odd but when you get the fieldname in the set it sets the value to everything in the field (And wraps it as a title).
As soon as you start to deal with fields that contain more than one title you need to change the way you refer to them so as to treat the field as containing titles eg the recommended use of each, or the Listops Operators
This difference between what the field contains and its components when titles are extracted is a helpful lesson in using tiddlywiki.
Regards
Tony