These three terms describe different ways of translating a design into screen-printed ink, and picking the wrong one for your artwork either drives up your cost unnecessarily or makes the final print look worse than the design file. Here's the difference in plain terms.
Spot color
Each color in the design gets its own screen and its own solid ink — a red is printed as flat red ink, not built from a mix of other colors. This is the standard approach for logos, text, and designs with a small number of distinct flat colors, because it produces the cleanest, most solid-looking color and the most consistent results between print runs.
Best for: logos, simple graphics, designs with 1-6 solid colors and no gradients or photographic detail.
CMYK (process color)
Uses four inks — cyan, magenta, yellow, and black — printed in overlapping dot patterns to simulate a full range of colors, similar to how a home printer works. It can reproduce more complex color blends than spot color with fewer screens, but flat colors and fine text can come out slightly less crisp than a dedicated spot-color screen.
Best for: designs with color blends or gradients that would need too many spot-color screens to reproduce individually.
Simulated process
A screen-printing technique built to mimic photographic, full-color artwork using a curated set of ink colors — more than CMYK's four, but still a fixed set applied as separate screens. It's the method used when a design needs to look close to a photograph while still being screen printed rather than digitally printed.
Best for: photo-realistic or highly detailed artwork on shirts printed via screen printing rather than DTG.
How this affects cost
Screen printing is priced largely by number of screens/colors. Spot color designs with 2-3 colors are typically the cheapest to run. CMYK and simulated process both use more screens to achieve complex color, so they cost more per design, though not necessarily more than a spot-color design with many individual colors would.
How to decide
If your design is flat colors and text: spot color. If it has smooth gradients but isn't photographic: CMYK. If it's meant to look like a photo: simulated process. If you're not sure which category your artwork falls into, a print prep service can tell you and prepare the separated files either way — see our print prep & color separation category.