2 Chainz RIPPED By Aries Spears -- You're NOT Different, You're LAME!

2 Chainz is not that different ... he's just another TERRIBLE rapper ... this according to former "MADtv" star Aries Spears.

Spears was walkin' around NYC yesterday when we asked about the current state of hip hop -- and for some reason, AS unloaded on 2 Chainz.

"I think 2 Chainz SUCKS," Spears said ... adding, "Have you heard the lyrics? All I want for my birthday is a big booty ho? Get some better rhymes 2 Chainz."

Spears continued ... "[2 Chainz] said when he shows up to the scene, he shows up with his roof missing, he's different . N**ga's driving a convertible ... if you wanna be different, show up in a horse and buggy."

FYI -- not everyone feels that way ... 2 Chainz has been nominated for multiple Grammys this year ... including Best Rap Album.