Guajillo chili and chili pepper are both types of chili peppers, but they differ in a few key ways.
Guajillo chili is a type of dried chili pepper that is commonly used in Mexican cuisine, particularly in the preparation of sauces and salsas. It is long and narrow, with a slightly curved shape and a deep red color. Guajillo chilies have a medium level of heat, ranging from 2,500 to 5,000 Scoville units (a measure of chili pepper heat).
Chili pepper, on the other hand, is a more generic term that can refer to a wide variety of fresh or dried peppers, including jalapeño, habanero, poblano, and many others. Chili peppers come in a range of sizes, shapes, and colors, and can vary widely in heat level, from mild to extremely hot.
So, in summary, guajillo chili is a specific type of chili pepper, while chili pepper is a more general term that can refer to many different types of peppers. Guajillo chili is a specific variety of chili pepper that is typically used in Mexican cuisine, while chili pepper can refer to a wide variety of peppers used in many different cuisines around the world.