Nixon's AG, was a bond salesman before being appointed, which counts sure, as AG is like the US Attorney for the whole country, but Giuliani was a line prosecutor, and made his way up to the US Attorney, they are both appointed positions, but AG can be just totally invalid like Bush pick, Alberto Gonzales. Usually, a US Attorney is a career prosecutor, who, if they leave for private practice, do it after their time in the US Attorneys Office. They are usually straight and narrow guys. Think like Comey, Christopher Wray, Rod Rosenstein, guys like that.