There has been quite some recurring discussion in this forum about filter quality, filter properties, differences in construction, and so on.
One of the largest filter manufactures is OEM for VW, Mercedes, Rolls-Royce, Volvo, and many others. They explain design, construction and subtle differences of common filters in their "Internet academy". Of course they put their own technologies in the foreground, but the realm of information is well worth looking at.
The link below leads to that academy. You can even take a test and get a certificate.
http://academy.filtron.eu/homepage