The difference between Conform and Knuckle under

Conform as a verb (intransitive, of persons, often followed by {{m, to):

}} To act in accordance with expectations; to behave in the manner of others, especially as a result of social pressure.

Conform as a verb (intransitive, of things, situations, etc.):

To be in accordance with a set of specifications or regulations, or with a policy or guideline.

Conform as a verb (transitive):

To make similar in form or nature; to make suitable for a purpose; to adapt.

Knuckle under as a verb (intransitive, idiomatic):

To yield or cooperate when pressured or forced to do so.