It's the difference between the "legacy" government (your traditionally elected public officials), and the "efficiency" government of bureaucracy. The legislature in the US has offloaded the power to make law to a multitude of bureaucratic agencies through the use of administrative law, as distinct from legislative law. Through the acts that establish these agencies, they are granted the power to create and enforce these administrative laws, which often leave the law-breaker with little recourse other than capitulation. The book National Security and Double Government by Michael Glennon is a fantastic resource for those interested in learning more.