I have noticed that each platform is becoming more and more for both personal and business usage. Originally, platforms would start as personal, such as Facebook, Instagram, and Snapchat. But now, all these platforms offer businesses the chance to promote on people's feeds, even if they are not be followed by said people. (This is personally a pet peeve of mine.) Overall, I would say that Snapchat stands out as the most personal, followed by Twitter and Facebook.
As I mentioned earlier, they are all used for business use; some more than others. It depends on the target audience. For example, if you want to reach out to middle aged women, Twitter may not be your first pick for a social media platform. If you want to reach a younger audience, Twitter or Instagram might get more response. I notice a lot more business related content on Instagram and Facebook. There is always something being promoted under "recommended for you".
I believe that Snapchat works well for both because the advertisements are subtle. They started putting advertisements at the end of snap stories, so you can't really see it coming. They are also in the explore section inside the special stories for the digital magazines on Snapchat, such as Cosmopolitan and People. You are only getting the ads because we have always expected them in magazines. I don't appreciate all the marketing on instagram and facebook. I just want to like and respond to the people I intentionally followed. (I am still obsessed with social media regardless.)
Random quote and a random pic of a lunar eclipse incase you don't wake up freakishly early like I do:
"A day without sunshine is like, you know, night." -Steve Martin