Choose the finish you want to live with.
Wood offers natural variation in grain and color. The species, grade and coating influence the finished appearance, and weathering changes the surface over time. A sample on the actual wood is more useful than assuming the color shown on a stain label will appear unchanged on an older deck.
Composite boards offer manufactured colors, textures and profiles, with differences between product lines. Compare the actual board, border and fastening arrangement rather than a small color swatch alone. Look at the sample outdoors and discuss how stairs, railing and exposed edges will coordinate.
A consistent appearance does not mean every board or installation will perform identically. Review the selected product information and the proposed construction details. The goal is a material choice that suits the space and care expectations, with no unsupported promise that its appearance will never change.