A Product Goal differs from a Sprint Goal primarily in Scope. While both are simple directional statements that provide an objective and purpose, the Product Goal applies to the entire Product Backlog, whereas the Sprint Goal pertains only to the Sprint Backlog. Each serves to motivate, direct, and measure progress but over different time frames.
The Product Goal is long-term, guiding the overall direction of the product, while the Sprint Goal is short-term, focusing on the immediate objectives for the current sprint. Achieving each Sprint Goal helps incrementally move the product towards fulfilling the Product Goal.