Comment by mgsouth

USPS - United States Postal Service (the governmental mail delivery organization). Not to be confused with:

- UPS, United Parcel Service (a for-profit; USPS is notoriously not-for-profit).

- UPS, Uninterruptable Power Supply

APC - Armored Personell Carrier -- military vechicle for transporting troops. Not to be confused with:

- APC, Formerly American Power Conversion Company, now an initials-only brand of some conglomerate, who coincidently make UPS units (the electronic device, not the delivery drivers).