The IRS disagrees, but obviously different legal contexts have different definitions, but I am aware of none supporting the distinction you are trying to make.
Example: Hatch Act provides that persons below the policy-making level in the executive branch of the federal government must not only refrain from political practices that would be illegal for any citizen, but must abstain from "any active part" in political campaigns.
In Garcetti v. Ceballos, the Supreme Court held “that when public employees make statements pursuant to their official duties, the employees are not speaking as citizens for First Amendment purposes, and the Constitution does not insulate their communications from employer discipline.”
Obviously, speech and debate clause controls for Federal Congress members.
[citation needed]
The IRS disagrees, but obviously different legal contexts have different definitions, but I am aware of none supporting the distinction you are trying to make.