Federal student loans can garnish your:
income tax refund and
Social Security benefits
The federal government cannot garnish your pension, disability benefits, retirement accounts, 401k, etc.
Private student loans can garnish your wages and bank account. They can also place a lien on your real estate, but only if they sue you and get a judgment. (Again, their ability to do those things depends on your state’s laws.)
Typically, private student loans don’t sue you right after you have a late payment or default. I mostly see them sue student loan borrowers when the statute of limitations is close to running out.