The network chose to censor elements of the American Idol star's controversial performance at the American Music Awards during a segment on its Early Show programme yesterday.
However, it later broadcast unedited footage of Madonna and Spears's kiss at the MTV Video Music Awards in 2003.
Speaking to Extra, a representative for the network said: "We gave this some real thought. The Madonna image is very familiar and has appeared countless times including many times on morning television.
"The Adam Lambert image is a subject of great current controversy, has not been nearly as widely disseminated, and for all we know, may still lead to legal consequences."
More than 1,500 viewers are thought to have complained following Lambert's performance on Sunday night, which also featured the singer simulating oral sex on stage.
Jarett Barrios, president of GLAAD, has claimed that the censorship "reinforces an unfortunate double standard that is applied openly to gay performers" but "applauded" the show for interviewing Lambert following the event.
Lambert recently admitted that he got "carried away" during the performance but insisted that he had not intended to offend anyone.