ICYMI, Kidd -- who started coaching the Mavs in 2021 -- recently said Doncic has surpassed Nowitzki in his eyes ... as the 24-year-old "does things that Dirk could never do."

Kidd was ripped for his comment ... especially since Dirk -- a 7-foot forward who can drain threes -- led the Mavs to their first NBA Finals title in 2011.

But Marion -- who was on that championship squad with Dirk and J. Kidd -- said people were mixing up what Jason truly meant ... and he doesn't think it was meant to downplay all Nowitzki did for the franchise.

"He's talking about the whole package," Marion told TMZ Sports. "He's talking about his skill set."

"He's not approaching [Dirk] in the accolades. There's no comparison [there]."

Marion is not taking anything away from Doncic ... pointing out the Mavs guard has amazing highlights at just the age of 24, including his recent 73-point game -- his career-high and franchise record.

Of course, old-school NBA fans would say Doncic can get so many points up because of the lack of defense in today's game ... but Marion -- who played 16 seasons -- says the game is just evolving at a faster pace.

"Layups are almost becoming null and void," the 45-year-old said. "They're making a conscious effort to get shots up within two passes."

"We ran systems, we had sets [in our era]. It's a big difference when you just running to score."