The R&B vet hit "The Breakfast Club" Friday to address her recent VladTV interview ... where she boldly declared Beyonce classifies as a rapper, while Diana Ross is the "epitome of glamour!!!"

Rather than backpedal, Stephanie doubled down ... explaining, in her eyes, Beyonce's last few albums have been more in the "hip hop" lane and no one -- Bey included -- can compare to the Motown queen!!!

Stephanie admits she's always been a Diana Ross "stan" -- she literally set the stage for Diana's portrayal of Dorothy in the 1978 film "The Wiz" after playing the character herself for years on Broadway ... but makes no apologies for her commentary.

She did deny the implication that her comments made it sound like hip hop and rap are beneath old-school R&B -- and she got some backup from guest host, Jess Hilarious.

Beyonce's 2022 "Renaissance" album was largely classified as "dance" and helped her break the record for the most Grammy wins ever. The entire album rollout was about glam ... word to the crystal holographic horse she posed on for the album cover.