There are three sets of resources I feel fall in between my definition of primary and secondary sources for genealogy. Primary sources are those records generated by our ancestors. They are contemporary and are the proper building blocks for genealogy. [They are not always accurate, but that is another discussion for another posting]. Secondary sources are compiled genealogies, county or town histories that is the product of someone else's analysis. Depending on that person, what time period they lived in, how well they used and cited their own sources, these works can be quite good or not so good.
In between are those works that are a bit of both worlds. The first such source are the Herald's Visitations of the 15th, 16th and 17th centuries in Britain. If your family had license to have arms (that is a coat of arms), these heralds visited you and wrote down your genealogy. Many of the manuscripts have been published as books per county in England. An example would be the Visitation of Surrey, in which may be three or four separate manuscripts of times visited going back to 1472 and as late as 1680.
These resources are great if your family appears in them. Of course, that means they had to be of a higher social standing in England. They are, or can be, very accurate within the generation or two (possibly three) of the person giving the information. They tend to be less accurate outside that. They also tend to be less accurate with females. Since arms and land were being passed down via agnate male lines, those lines were remembered more than their sisters who married outside the family. Again, in the generation of the provider of the information, he may get his sisters and even his aunts correctly, but further back may not. Cadet lines (those lines stemming from younger sons), also suffer more in accuracy.
These records are primary insofar as they are contemporary (within a generation) and are being generated by an ancestor or, at least, a close relative of an ancestor. They are secondary when they rely on the remembrances of generations further back and family further afield. Visitation records are great jumping off points, but should always be corroborated with other primary records such as wills, court records, IPMs, etc.