Hi Maika! Thanks for this question! Construct and content validity are closely related but distinct concepts. Construct validity refers to how well a test measures the abstract concept it is supposed to measure. In this case, does the survey accurately measure quality of life or is it testing some other construct (depression, stress, mood, etc.)?
Content validity refers to how representative a test is to all aspects of the construct. For example, does a quality of life measurement assess all domains of quality of life (physical, psychological, social)? If relevant aspects are omitted or irrelevant topics are included, content validity is threatened.
Another way to think about it is that construct validity relates to the test as a whole while content validity relates to the questions. A test with low content validity or criterion-related validity likely also has low construct validity. For this question, the researcher determines that the new survey does not sufficiently measure quality of life. However, we don’t have details about what is lacking (Is it related to the content of the questions? Does it not correlate well with a gold standard QOL assessment?). Therefore, we can only definitively conclude that construct validity is lacking.
For further clarification, here is a nice article that summarizes the types of validity: https://www.scribbr.com/methodology/types-of-validity/
Hope this helps!
Chrissy