PSD and AI are both Adobe formats, but they store fundamentally different types of graphics. Choosing the wrong one means either losing quality when scaling or fighting the wrong tool for your task.
PSD (Photoshop Document) stores raster graphics — images made of pixels. Every photograph, digital painting, texture, and screen-captured image is raster. PSD preserves Photoshop's full editing state: layers, masks, filters, adjustment layers, and blend modes. It's the working format for photo editing, compositing, and pixel-based design. The limitation: scale a raster image up and it gets blurry.
AI (Adobe Illustrator) stores vector graphics — images made of mathematical paths and shapes. Logos, icons, typography, diagrams, and illustrations are typically vector. AI preserves Illustrator's full editing state: paths, anchor points, gradients, type objects, and artboards. Vectors scale to any size without quality loss — the same AI file works on a business card and a billboard.
The simple rule: if it started as a photo or contains photographic detail, it's PSD territory. If it started as shapes, lines, and text, it's AI territory. Many design projects use both — a poster might have a PSD photo layer composited with AI vector typography.
For cross-application compatibility, export to PNG (raster) or SVG/PDF (vector) depending on the content type. PSD and AI are working formats; final delivery should typically be in a universal format.