Kelly Clarkson doesn't compare to Beyonce -- because Kelly actually sang her song LIVE yesterday at the Presidential Inauguration ... TMZ has learned ... unlike Beyonce, who lip-synced to a pre-recorded track.
A spokesperson for the U.S. Marine Corp Band -- which provides the music for the Inauguration -- tells TMZ, Beyonce mouthed the words to a pre-recorded studio version of "The Star-Spangled Banner."
But the rep added, Kelly sang "My Country 'Tis of Thee" WITHOUT the help of a backing track.
The rep said it's standard procedure to record a backing track before a live performance such as this -- you know, just in case -- and Bey decided at the last minute to rely on the studio version instead of winging it in person.
The rep added, "We all know Beyonce can sing ... We don't know why she chose to use the pre-recorded track."