Principal and Distinguished are, usually, titles added to convince HR to pay market salaries.

    Mgr: "We'll need $140k to get him."
    HR: "The band for Senior Engineer is $100k to 125k."
    Mgr: "So you can't do $140?"
    HR: "Nope."
    Mgr: "What if I hire him for a *Principal* Engineer position?"
    HR: "I need to talk to the CFO about whether we need Principal Engineers."