What is the difference between cyclopedia and encyclopedia?

The words "cyclopedia" and "encyclopedia" are essentially synonymous. They both refer to a comprehensive reference work that provides information on a wide range of subjects.

However, "encyclopedia" is the more common and preferred spelling in modern English. "Cyclopedia" is considered an older and less common spelling, often found in older publications or in certain specific contexts.

There is no real difference in meaning between the two words. They both encompass the same concept of a multi-volume reference work with entries on a broad array of topics.

So, while you can use either term, "encyclopedia" is the standard and widely recognized word in contemporary English.