Updating from two prone outlets to three prone outlets

[Benjamin Beyer]

Hi BP Nation,

I am currently house hacking a two-family home in Milwaukee, WI. I've been making updates throughout the property as needed and one of the things I noticed is that all the outlets upstairs are "three prone outlets" (Like the ones you'd see in a modern house), while all the outlets down stairs are two prone outlets. I am wondering if anyone has see this before and knows why that would be. 

Also, do anyone know how I would update the downstairs outlets? Is this a project I could handle? I've replaced outlets before but do I need to run wire to do this update?

Thanks!