Vue: rendering output defined primarily with templates and attributes like `v-for`; Single-File Components structure, lets you define styles as CSS and I _think_ they get scoped automatically; all major libs for routing, state management, etc, are considered "official" Vue packages and have at least some intentional coordination; probably less ecosystem churn overall due to those "official" packages; possibly easier to get started with, since it's easier to drop in one script tag and use it as a small enhancement to an existing page; reactive data UI for updating state (`state.value = 123` auto-triggers UI updates of components that rely on that data).
React: JSX syntax for rendering logic ("It's just JS!"); no official structure for defining component files/folders/logic; React is still "just a rendering lib/framework", so all other capabilities (routing/state management) are filled in with community maintained packages (React Router, Redux, etc); _dozens_ of community packages for any conceivable use case, but plenty of churn as a result; _can_ be used with just a couple script tags, but in practice normally used with a full JS build toolchain; explicit `setState(newValue)` API for triggering re-renders, and renders many components by default - have to intentionally optimize components to avoid unnecessary re-renders.