Chapman rang Adelaide radio station FIVEaa on Wednesday night after Demetriou was interviewed earlier in the evening.
When asked why Essendon's draft sanctions were not more severe than those handed to Adelaide, Demetriou said the Bombers had been more cooperative.
"This club [Essendon], unlike the Crows, cooperated fully – they actually self-reported – they came to us," he said.
"From the chairman through to the coaching staff, through to the staff, through to every player, every individual at that club cooperated fully and openly with ASADA and the AFL and the investigation.
"That carries weight in sanctioning.
"I've got to tell you, when we dealt with Adelaide that didn't happen."
Chapman said he was in a meeting when the interview aired but rang the League boss after he began receiving phone calls alerting him to Demetriou's comments.
"I've just spoken to Andrew Demetriou…and I said, 'Andrew this is what people have just told me you said – that's crap'," Chapman said on FIVEaa.
"[At the time of the salary cap breach] I personally rang Andrew Demetriou and I said, 'mate I think we've got a problem'.
"He said to me, 'Rob, I thank you, you've done the right thing and in the event that some sanctions have to be applied because you've done the wrong thing, this will hold you in good stead.'
"I just repeated that story to Andrew and he said, 'you're absolutely right, I recall it vividly'."
Chapman said he had asked the AFL for assistance and suggested the club needed an "investigative accountant" to go through its files.
"That's compliance 101," he said.
The Crows chairman said he was unsure whether Demetriou's comments comparing the two clubs were taken out of context or whether he simply didn't mean to say what he did.
"You'll need to get him back on the phone – Andrew's a smart bloke and he doesn't have seniors moments," Chapman said.
Chapman pointed out that the penalties handed down to the Bombers were "the heaviest handed down to an AFL club in history", describing the club's $2million fine as a "big hurdle".
But he wouldn't comment on the severity of Essendon's penalties compared to his own club's.
"We got our result, they got their result and it's imprudent of us to even comment on Essendon," he said.
