In the past there were font rendering problems between Win and Mac. It seemed that the issue had been solved but it just wasn't as apparent.
When in Preview mode issues appear only at certain font sizes and monitor resolutions. Printing them comes out fine.
The problem may be 'not as bad' on the later ver of Win 10 but Microsoft considers it a legacy problem (I read) and has no intention of changing anything.
Fundamentally Mac and Win are just different.
See this article for more information: https://en.wikipedia.org/wiki/