What is the difference between a Sheriff's Department and a Sheriff's Office and why should it matter?

Black’s Law Dictionary defined the terms as follows:

DEPARTMENT: “One of the major divisions of the executive branch of the government . . . generally, a branch or division of governmental administration.”

OFFICE: “A right, and correspondent duty, to exercise public trust as an office. A public charge of employment. . . the most frequent occasions to use the word arise with reference to a duty and power conferred on an individual by the government, and when this is the connection, public office is a usual and more discriminating expression… in the constitutional sense, the term implies an authority to exercise some portion of the sovereign power either in making, executing, or administering the laws.

The Office of Sheriff is NOT simply another “department” of county government. The internal operation of an Office of Sheriff is the sole responsibility of the elected Sheriff. County department heads are subordinate to a county governing body, because a “department” is truly only a division of county government. The Office of Sheriff is a statutory/constitutional office having exclusive powers and authority under state law and or state constitution. These inherent powers are not subject to the dictates of a local county governing body. The Office of Sheriff has inherent common law powers and sovereignty granted under a state’s constitution and/or state law. It is different from a county department which derives its limited authority from whatever is delegated to by statute or by state constitution.

The use of the “Department” implies being a subordinate unit of government (i.e. subordinate to local government – “delegated” authority from county government to department). The use of the term “Office” implies inherent powers and independent sovereignty.

(Found at www.aransascounty sheriff.com, derived from the Sheriff Association of Texas.)

Link to 
National Sheriff's Association