red chilli powder
“Chili” and “chili” usually refer to the same thing in English, namely chili peppers. However, there may be some subtle differences in usage and meaning, depending on the context and regional customs. Here are some of the differences:
Spelling Differences
“Chili” is the common spelling in American English.
“Chilli” is the more common spelling in British English.

Differences in Meaning
“Chili” can refer to the plant or fruit of chili peppers, or to dishes made with chili peppers, such as chili con carne.
“Chilli” usually refers to the plant or its fruit, especially in the United Kingdom and other Commonwealth countries2.
Differences in cuisine
In the United States, “chili” often refers to a bean-free chili con carne, which is a Texas-style chili soup. In the United States, “chili” often refers to a bean-free chili sauce, which is Texas-style chili.)
In the U.S., “chili” often refers to a bean-free chili sauce, which is a Texas-style chili soup, while in the U.K. and other Commonwealth countries, “chili” may be used more often to refer to the chili pepper itself, rather than a specific dish.
Contextual differences
When talking about an ingredient like chili peppers, the two may be used interchangeably.
When talking about a specific dish or condiment, different spellings may be used, depending on regional customs.
Overall, the difference between “chili” and “chili” is mainly in spelling and regional usage, and in most cases they can be considered synonyms.