Not sure if this is the place for questions about computer history, but I always like knowing more about the early choices that were made in Silicon Valley which distinguished operating systems from one another on purely aesthetic levels. There always seems like there's a fun or quirky story about those, and so I wanted to know if even desktop alignment (as in, where your items default to residing on your desktop; top-right on pretty much every Mac OS I've ever run, and top-left on your typical Windows OS and Linux) has a story behind its divergence among the platforms.
Just a quick moderator reminder to OP and potential respondents: /r/AskHistorians has a "20-year rule" which prohibits discussion of current affairs, i.e. events/conditions within the last 20 years. As such, answers will have to confine discussion to pre-1995 only. In addition, be mindful of other sub rules and avoid anecdotes, opinion, speculation.
OP, since the 20-year rule takes a pretty serious bite out of the history of these operating systems (here are the timelines for Windows and Mac releases), you might consider x-posting this to a sub with a focus on computing, specifically GUI design/usability.