Presbyterian government is not simply episcopal government with the bishops removed. It is a system of courts, each made up of ministers and elders sitting together with equal voice, and each answerable to the one above it.
The kirk session is the court of a congregation, chaired by its minister and composed of elders ordained for life. Above it the presbytery covers a district, is made up of every minister in it together with an elder from each congregation, and is the body that ordains, inducts and disciplines ministers and that has to approve a great deal of what a congregation wants to do. Above that the General Assembly meets once a year, decides what the church holds and how it is governed, and elects a Moderator to chair it for that year and no longer. The Moderator is a chair rather than a leader, and the deliberate absence of a permanent head is a doctrinal position and not an administrative convenience.
Two features follow from the design. Elders are ordained, not appointed, and the parity of minister and elder in every court means that a congregation is never governed by clergy alone. And because the Assembly is sovereign, a change in the practice of the church requires it to pass through the presbyteries as well, under the Barrier Act of 1697, which slows every contested decision by at least a year on purpose.