というものだ・ということだ: the difference
というものだN2
Meaning
Speaker's impression, Criticism or conclusion
Past papers
Tested 2 times in past papers
Example
その言い分はわがままというものだ。
That excuse is just selfishness.
ということだN3
Meaning
I heard that, Rumor has it that, It is said that, It means that
Past papers
Tested 2 times in past papers
Example
人によって考え方が違うという事だ。
That means different people think in different ways.
How to tell them apart
「というものだ」: the speaker's strong personal judgment. 「一人で全部やるのは無理というものだ」 (Doing it all alone is simply too much).
「ということだ」: hearsay ('I hear that ...') or an objective explanation ('that means ...'), with no personal judgment. 「彼は来月結婚するということだ」 (I hear he's getting married next month).
Its negative counterpart is 「というものでもない」 (not necessarily).