Verisimilitude, or truthlikeness, is the idea that one description of reality can be closer to the truth than another. Think about models in science, where older models are often not simply discarded as false. Instead, a newer model is just better. It may explain more, predict more accurately, and correct errors in the older one. In that sense, one model can be more truthlike than another.
Truth is alignment with reality. It begins with correspondence to the material world. An idea is true within its scope when it aligns with the reality it describes and does not conflict with it. At the same time, complex representations can vary in accuracy, completeness, precision, and scope. One model can represent reality better than another; Neither model is reality itself.
While verisimilitude is mainly concerned with comparative truthlikeness, TST separates several related questions. First, is the true or false category of an idea within its applied scope. Only after that first step do we then dive into how completely the idea aligns with reality. A simple proposition may be binarily true, while a larger model can still be more or less truthlike. Understanding that difference matters because it keeps us from making two common mistakes: treating an incomplete model as false simply because it is incomplete, or treating all models as equally valid.
TST incorporates the same useful insight while grounding it in the Split between reality and ideas. Reality is determinate. Ideas are representations. Truth is correspondence within scope, while degree of truth concerns how well a representation captures reality. The wisdom is to hold both ideas at once: trust what has earned truth status within its scope, while remaining humble about how much of reality the model actually captures.