The short answer
A vector image stores shapes as mathematical descriptions - points, lines, and curves - so it can scale to any size without losing sharpness. A raster image stores a fixed grid of pixels, so it captures photographic detail but blurs when enlarged past its resolution. Illustrator is a vector tool; Photoshop is a raster tool. Choosing between them is really choosing which of these two models fits the job.
Vector (Illustrator)
Because a vector is math, it is resolution-independent: the same logo file prints crisp on a business card and a building. Files stay small regardless of output size, and every shape remains editable. The tradeoff is that vectors cannot represent the continuous, subtle tones of a photograph. Vector is the home of logos, icons, type, and illustration.
Raster (Photoshop)
A raster image is a grid of pixels, each with its own color - the natural format for anything with photographic richness. It captures gradients, texture, and detail that vectors cannot. The cost is resolution dependence: enlarge past the pixels you have and the image softens or blocks up, and high-resolution files get large. Raster is the home of photography, painting, and detailed retouching.
Side by side
| Vector | Raster | |
|---|---|---|
| Stores | Shapes as math (points, curves) | A grid of colored pixels |
| Scaling | Infinite - sharp at any size | Fixed - blurs when enlarged |
| Best for | Logos, icons, type, illustration | Photos, painting, retouching |
| File size | Small, independent of output size | Grows with resolution |
| Tool | Illustrator (also Figma, Inkscape) | Photoshop (also Lightroom, GIMP) |
| Formats | SVG, AI, EPS, PDF | JPG, PNG, WEBP, TIFF, PSD |
When to use each
- Making a logo or icon? Vector, always - it has to scale from favicon to signage.
- Editing a photo? Raster - there is no vector version of a photograph.
- UI design? Mostly vector (shapes, text, icons) with raster images placed inside - which is why Figma is vector-first.
- Both? Common. A poster might be a vector layout with a raster photo placed in it.
File formats
The format usually tells you the model. SVG is vector and ideal for web icons and logos because it scales and stays tiny. PNG and JPG are raster - PNG for graphics with transparency, JPG for photos. When someone asks for a logo "in vector," they mean SVG, AI, or EPS - not a PNG blown up to fit. Two ambiguous cases worth knowing: PDF is usually vector but can be raster, depending on the app that made it, and TIFF and PSD are raster working formats you will meet in print and photo pipelines.
Telling and converting
The quickest test needs no file extension: zoom in or scale the image up. If edges stay crisp at any size, it is vector; if it goes blurry or blocky, it is raster.
- Raster from vector is easy. Export the vector at whatever pixel size you need - this is what every SVG-to-PNG export does. Information is only lost in one direction.
- Vector from raster is a trace. Illustrator's Image Trace rebuilds shapes from pixels. It works well on flat, high-contrast art like a scanned logo, and poorly on photographs - there is no clean vector version of a photo.
- Compatibility differs. Raster formats open in any browser or viewer; vector working formats (AI, EPS) often need design software. For sharing on the web, SVG is the vector format everything understands.