It's not a dumb question at all. Here's a simple answer that I think may help clarify.
Presbyterian is simply one denomination under one much larger umbrella which is used to categorize a framework or lens for viewing God, the world and scripture.
Think of two frameworks like we have mammals and reptiles. These two broad groups are the two main systems of theology - Dispensational and Reformed/Calvinist.
- We can think in broad terms of Christianity having two umbrellas - Catholic and Protestant. [While there are thousands of denominations, they are all basically under one of these two- Catholic or Protestant.] Eastern Orthodox may be an exception, but the priests, and liturgy and church government make it closer to Catholocism.
- So also, it's helpful to think of Protestantism as two large umbrellas - and that 98% of all denominations can be grouped under one of these two camps or umbrellas. Dispensational and Calvinism [Reformed Theology] Reformed Theology or Calvinism is the broader theological framework, or the lens through which they see God and how they interpret scripture.
Within this broad framework are many denominations of protestant Christianity, and Presbyterian is the largest and most well-known denomination.
Another way of putting this is that Dispensationalism is another lens or system of theology.
Baptist is the largest and most well known denomination which is dispensational.
Most Presbyterians are reformed/ Calvinists, but not all Calvinists are Presbyterian denomination.
In the same way, - most Baptists hold a dispensational view of theology - but not all dispensationalists are Baptist denomination.
There are Reformed Baptists, and independents, and Evangelical Free, and Christians who are Calvinist but not officially part of a denomination.
But Calvinism [Reformed Theology] and Dispensationalism are the two primary systems or lenses, and have very little overlap, so it's not possible to be a Dispensational Calvinist.
Presbyterians or Calvinists have a totally different lens or framework for interpreting end-times, and their entire approach to salvation and eschatology to free will and the role of Israel is entirely different from a Nazarene or Pentecostal, or Church of God.
Dispensationalism refers to the view that there are very specific different time periods in History, and how God interacted with his people in these different dispensations. The most common view is that there are seven different dispensations and now we are in the "Church Age", and most dispensationalists agree that Israel is a real nation, and that it has a unique role in end times events.
In sharp contrast, most Calvinists believe that the Church is Israel, or that the Church replaced Israel, and they would say that many of the passages and promises now apply to the church and Israel and many passages in Daniel and Revelation are viewed as symbolic, and not literal.
Nazarenes, most Pentecostals, most Seventh Day Adventists, most Southern and Free-will Baptists, Holiness, Bible Methodists, United Methodists, Wesleyan, and most Charismatics and most Church of God are Dispensational and therefore, not Calvinist or not Reformed Theology.