Adobe's Photoshop and Illustrator are both best-in-class graphics applications, but they each have a different focus. It can be confusing to know which app is best suited to a particular project, so we are here to help. Read on to learn about the differences between the two programs and when to use each one.

The differences between vector and raster images

Before diving into the particular features of both Photoshop and Illustrator, it's important to understand the two types of graphics that can be created: vector and raster. Vector images are created using mathematical constructs (hence the term vector) which are recalculated when scaling the image up or down. Raster images, on the other hand, are composed of tiny pixels. Pixels are arranged side by side in a grid format, and you can actually see them when you zoom in on a raster image.

Uses of vector images

Because vector images actually contain the mathematical equations to redraw shapes, these images can be viewed at any resolution without losing quality. The images below show a vector graphic of a lion side by side with a close-up view of one detail. Notice that the lines are very crisp and exact, even close up.

Because the image can be scaled very large or very small without compromising quality, vector images are ideally suited for printing. If you are creating an image that will be used in a variety of ways, particularly if it might need to be printed, then it's best to create it as a vector image. Vector images are the most flexible in terms of their use.

Common file types for vector images include:

• Scalable Vector Graphics (.svg)
• Enscapsulated PostScript (.eps)
• Portable Document Format (.pdf)
• Adobe Illustrator (.ai)

Uses of raster images

Raster images, due to their pixel level granularity, have a limit to how big they can be scaled without losing crispness. The images below show a raster image of a lion side-by-side with a close-up detailed view. Notice that that the full size image looks crisp, but the edges become fuzzy when zooming in on a detail or enlarging.

The benefit to raster images is that you have the ability to edit the image very specifically, down to each and every pixel, but there is a trade of scalability. While you can't use a raster image for every application, the resolution is usually more than sufficient for digital graphics that will remain online or for a small printed item. This type gives you the most control over image editing and is preferable for this flexibility.

Common file types for raster images include:

• Joint Photographic Experts Group (.jpg or .jpeg)
• Portable Network Graphics (.png)
• Graphics Interchange Format (.gif)
• Tag Image File Format (.tif or .tiff)

When to use Illustrator

If you are going to be creating a vector image from scratch, you will need to use Illustrator, as it is the only Adobe app that creates vector graphics. Any image you create in Illustrator will be created as a vector graphic, although you do have the ability to save a rasterized copy if you'd like. You can also edit vector graphics in Illustrator, making changes or adding new details.

You can open a rasterized graphic in Illustrator; however, you will not be able to edit the underlying details because the vector information does not exist. Illustrator does provide tools to generate a new vector image based on a raster graphic, which can be very useful in some situations. If you created a company logo as a raster graphic, for example, but now need to create a vector version in order to print a banner or large shop sign, then Illustrator is the perfect app to accomplish that.

When to use Photoshop

Photoshop was originally designed as a photo-editing application, so it will be your first choice for editing photographic projects. It provides an endless number of filters, tools, and effects that you can apply. It additionally gives you the ability to create multiple layers, and to edit down to the pixel level. If you are creating a graphic that does not need the scalability of a vector image, such as graphics exclusively for use on the web or a business card, then Photoshop allows the most flexibility in creating your art and is generally the easier app to use.

While Photoshop can open vector graphics and edit them, the imported image will be rasterized, and the changes will not be available in vector format. It is relatively common to do this in order to make use of the advanced image editing tools in Photoshop.

Can you use both?

The good news is that using Photoshop and Illustrator is not an either-or decision. The file types are compatible between both applications, but you must understand the implications if you decide to convert a vector image to a raster graphic. There are applications available to convert standard images to vector format, but it's best to choose the correct image type at the beginning if you are able to.

It is also possible to link images between Photoshop and Illustrator, which can be useful. Using a link allows you to make changes to an image in one app, and then have the changes automatically reflected within a project using the other. For example, a Photoshop project of a person wearing a t-shirt can be linked to an Illustrator file with the t-shirt graphic. Keep in mind, however, that the underlying differences between vector and raster images still apply.

Use the best application for your project

Adobe's Creative Cloud Suite offers a variety of apps for working with photos and digital graphics. Which tool to use can sometimes be confusing, but if you understand the differences, you will be able to choose which is best for your project. Now you not only know the difference between Photoshop and Illustrator, but between vector and raster graphics as well.