The following paragraph:

>  In the first case, every single 'item' in the questionnaire must be specified, including all 'display' items, groups, etc. Re-use is limited to question text, value set, data type and other information that can be determined from the referenced definition element. On the other hand, with modular questionnaires, multiple items can be defined along with display text, enableWhen logic and other questionnaire characteristics. The first approach is best suited for "data-element"- based questionnaires and the latter for defining collections of questions. (While defining separate modules for every single question is possible, it would be quite a bit of overhead). 

Seems to be talking about the two above bullet points in reverse order, referring to the contents of the 2nd bullet point as the "first case".