Conservative was a mixture of many elements. Observant maskilim, like saul lieberman, total kofrim, like Mordechai Kaplan, and a lot in-between, but the common denominator was a break from mesorah and an embrace of modernity, a need to revamp yiddishkeit to save it in America… Which is basically what most of MO wanted to do as well.
This is why rav aharon says that the two are not very different.
The only differences were how far they would go, how much they would sacrifice to “save” whatever Judaism was left in their world. MO sacrificed kedushah, letting its people swim and dance mixed and barely teaching tznius, and conservative allowed people to drive on Shabbos.
But conservative was worse than MO, because while MO only gave tacit approval for their sins, conservative openly declared that driving on Shabbos was allowed, and many, many other issurim.
Failing to give mussar may make one culpable, but it’s not the same level of heresy as publicly announcing that sins are allowed.
That’s aside from the issue of many in the conservative world stating disbelief in torah she baal peh, or chumash… But MO had a tolerance threshold for heretical beliefs as well.