According to the Cambridge Dictionary, above all means most importantly and primarily means mainly. But some people may be confused by the difference between "most importantly" and "mainly". I can mostly feel the difference but I'd like to get more ideas about how to explain the difference between the synonyms "above all" and "primarily" better. Thank you!
In the hands of careful writers, above all signals absolute primacy, while primarily indicates relative primacy.
Because of lack of sufficient nursing staff and above all lack of patient care, a good deal of antagonism exists between relatives and nurses…
From a nurse’s point of view, insufficient staff may be the cause of lack of care, but for the families of patients, it is the source of antagonism, all other possible reasons fading into the distance.
How does hospice care work? In general, the care of the patient is primarily managed by a family member, and this family member also helps make decisions on behalf of the patient.
Many people — other family members, friends, professionals — may provide care for a hospice patient, but first among them is a primary caregiver, in most cases, a particular family member.
Writers frequently use either or even both expressions to move from a broader topic to one more specific:
Two essential findings have to be emphasized in the formation of data processing in the service sector, above all in the field of transport. Primarily a drastic structural change is going on in this sector, assigning new tasks concerning logistics to transport companies.
This writer first wishes to narrow a discussion of the broader service sector of the economy solely to transport, then present two essential findings; the first of two is the structural change. Were these findings not already limited to two, the writer could go on to mention any number of other findings of which the structural change is the most important.
But above all, decorative arrangement is evident in music. Motifs are developed, abandoned for a moment and taken up again: they alternate, they interconnect; not only do they explicitly describe states of mind, they are also united to create an overall harmony.
Wherever else decorative arrangement is found, say, in architecture, it is music where it is most manifest. While there may be some relativity, primarily would be too bland a beginning for the following detailed description of how composers employ decorative arrangement. By using above all, the writer is telling the reader, “Forget anything else I've said before; I’m going to talk about music.”
In the hands of less skilled writers, the distinction between above all and primarily can be obscured:
The first and more primary step is kinetically oriented. As such, it refers to the Kantian transcendental aesthetics stricto sensu, except that (last, but not least !) for Kant, sensations are not primarily moved and moving, but are, above all described as a “Gewühl der Empfindungen” (chaos of sensations).
This writer begins with a double tautology: first and primary mean the same, so we have the kinetically oriented step as first and *firster, but — last but not least — sensation is not directed motion, but chaos, which is a far more apt description of this sentence than it is of Kantian philosopy. Despite this confused concatenation of priorities, however, the writer is trying to tell you that Gewühl der Empfindungen is the whole enchilada.
Speaking of tautology:
What I'm above all primarily concerned with is the substance of life, the pith of reality.
What this sentence does suggest is that if used together, above all as the stronger, absolute term will usually come first before the relative primarily.