Note that I said "physical format". As you have encountered, different platforms used different logical formats for the same 3.5 inch floppy, not only IBM PC and Apple Mac but also Commodore Amiga and more. Generally these was based on the logical format the vendor previously used for older floppies. BTW, IBM was quite late in adopting the 3.5 inch microfloppy, only doing soon after the Mac Plus was released in 1986 with the IBM PC Convertible.