Liberalism is a specific error that makes a proper good superior to the common good, namely the potential to act either for good or evil indifferently. The bespeaks of a genus of errors defined by making a proper good superior to the common good.
Tyranny is a specific example of the genus which is not itself a species of liberalism. In a tyranny (i.e. a degenerate form of monarchy), the tyrant seeks his own proper good over and against the common good over those whom he has authority. That is the object of his authority becomes his own proper good and all the the subsequent impossibility of such and the lack of obedience that such commands would otherwise entail.
In some ways, liberalism attempt to make a million tyrant, because it aims, theoretically if not actually, at the proper good of every individual and each seeking their proper good over the common good. In a manner, a liberal society is maximally tyrannical in that it seeks to make everyone a tyrant.
A concrete and proximate example of this error are jeans days. Recently my company announced that jeans are acceptable every day of the week, because “we want everyone to be comfortable.” Ignoring for a moment those people who are uncomfortable working in a professional environment where no one dresses and therefore looks professional, this is explicitly about raising the proper good of comfort over the common good of order and professionalism.
A curiosity is who is the mother and who are the daughters for all of the errors are connected in various ways and tend to create and reinforce one another.
One potential goes back to Ockam’s denial of the existence of real relations, which tends toward nominalism, Protestantism, and Liberalism.