A pedigree chart is a standard genealogical form that typically provides space for information about four generations, while a family tree can be any type of diagram indicating ancestral relationships. Family trees may be decorative, provide more or less information than pedigree charts, or be printed on nonstandard-size paper.
Genealogists use pedigree charts in conjunction with family group sheets to compile family history information in a standardized and easy-to-read way. The pedigree chart focuses on the direct lineage of one individual, who is assigned the number 1. The chart branches outward with details of the individual's parents, numbers 2 and 3; each parent's parents, numbers 4, 5, 6 and 7; and each grandparents' parents, numbers 8 through 15. Family group sheets allow extra space for additional information about each marriage or union in the pedigree chart, including details about other children. Because these forms follow widely used formats, individuals can easily share information with other family history researchers, and the pedigree chart's numbering system aids in keeping track of ancestors who have the same names.
Pedigree charts are family trees, but the term "family tree" encompasses all types of diagrams that explore family heritage. Family trees can cover dozens of generations or only a few, and they can include as much or as little information as desired.