Beyoncé Lip Sync? Kelly Clarkson -- Sorry Beyoncé, I Sang LIVE at Inauguration

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 added, "We all know Beyonce can sing ... We don't know why she chose to use the pre-recorded track."