Job titles mix these words freely, so look at the deliverable. If the output is a video file, it is motion graphics work. If the output has to react to taps, data and states inside an app, it is UI or product motion design.
What carries over
Easing, timing, spacing, hierarchy and storytelling apply to both. A motion graphics artist who understands the 12 principles of animation has a head start in UI motion.
What is different in UI
UI motion must be short, interruptible and repeatable thousands of times without getting annoying. It must run on real devices and respect accessibility settings. It is usually designed as states rather than as a single timeline.
Tools
For video: After Effects, Cavalry, Blender, DaVinci Resolve Fusion. For UI: Figma prototypes, ProtoPie, Rive, ExodeUI, Lottie, and code libraries such as Motion and GSAP. We make ExodeUI.