RNs go through a nursing program (many options and levels of degree), then take an exam for a license. Most RNs I interact with have an associates degree, but many have BSNs and MSNs.

SFAs technically don't need anything more than a high school diploma. These days, most SFAs are certified by 1 of 2 associations. To be able to take the certification exam, you must complete an FA program (typically 2 years didactics plus about 500 cases). The majority of SFAs started as STs (surgical technoloists). To be an ST, it's pretty much the same steps. Both of these programs only give a certification. Most STs I've interacted with just have a HS diploma, while a good portion these days have an associates degree. Some SFAs have bachelor's degree and sometimes even a masters.

SFAs have a much more specific role in the medical field. They work strictly in surgery, while RNs have a much larger scope.