Hello! I am new here and had no idea about the world of free pdf's until now. I had a couple of questions regarding these websites:

Which is safer? Can I use either?

What are the chances of me getting a virus from any one of these two sources? How do I check a file before downloading it onto my computer?

Will I get in trouble for using these versions of textbooks? (I'm in the US)

I'm not super tech-savvy so please feel free to "dumb it down" for me