I know folks are obsessed with market cap for some reason, but I'm curious here: what portions of either company are public vs. privately held? Is there a mater

I know folks are obsessed with market cap for some reason, but I'm curious here: what portions of either company are public vs. privately held? Is there a material difference we should be considering here as a multiple instead of basic "outstanding shares * share value" to make this apples to apples? For example, if outstanding shares are 95% of MS, but only 92% of Apple's equity, etc. I couldn't find this information myself in a cursory search, but I'd gather it's easy enough to find out if you know where to look. Thanks for the help.