What is the difference between "mountain", "hill", and "peak"; "lake" and "pond"; or "river" and "creek?"

There are no official definitions for generic terms as applied to geographic features. Such definitions as exist derive from the particular needs and applications of organizations using them. The Geographic Names Information System (GNIS) database utilizes 63 broad categories of feature types originally defined solely to facilitate retrieval of entries with similar characteristics from the database.

These categories generally accord with dictionary definitions, but not always or in all respects. The differences are thematic and highly perceptive. For example, a lake is classified in the GNIS as a "natural body of inland water," a definition that may not apply in other contexts. We have found 54 other generic terms with characteristics similar to a lake, and all are classified as lake, including features called ponds. It might be generally agreed that a pond is smaller than a lake, but even this is not always true.

All "linear flowing bodies of water" are classified as streams in the GNIS. At least 121 other generic terms fit this broad category, including creeks and rivers. Observers might contend that a creek must flow into a river, but such hierarchies do not exist in the Nation's namescape. Near the USGS offices in Northern Virginia, Little River flows into Goose Creek. Many controversies exist, such as mountain and hill, which we call "summit" along with 194 generic terms with similar characteristics. Cities, towns and other entities with human habitation are classified as populated places.

The British Ordnance Survey once defined a mountain as having 1,000 feet of elevation and less was a hill, but the distinction was abandoned sometime in the 1920's. There was even a movie with this as its theme in the late 1990's - The Englishman That Went Up a Hill and Down a Mountain. The U.S. Board on Geographic Names once stated that the difference between a hill and a mountain in the U.S. was 1,000 feet of local relief, but even this was abandoned in the early 1970's. Broad agreement on such questions is essentially impossible, which is why there are no official feature classification standards.