Defining creationism

Creationism has a variety of definitions depending on who is using the term. Frequently it is used as a shorthand to Young Earth Creationism, sometimes to the consternation of those who hold to what they consider creationism but don't think the earth is young. Their complaint has some validity, but the cumbersome term Young Earth Creationism invites itself to be shortened. Biblical Creationism has been suggested as an alternative to Young Earth Creationism, especially considering that 6000 years is not really that young. I am not in favour of this. Though I think the Young Earth Creation position is biblical, it not as if other creationists all think their positions are unbiblical. Even if Old Earth Creationism turns out to be unbiblical it is premature to anticipate the outcome of the debate. Literal Creationism would be an alternative to Young Earth Creationism if it were not for the problem that literalism is frequently misunderstood to mean hyperliteralism.

I am not a great fan of eponyms though that is often the outcome. Descriptive labels are good. Perhaps the best labels are those invented by one's opponents so long the term is acceptable to its adherents.

Old Earth Creationism may include ideas such as Progressive Creationism and Gap Theory. I think it preferable to group the major positions logically, then discuss the variants within a general position.

Here are several positions. I have tried to describe the position as viewed by adherents, feel free to correct me if you think I have misconstrued your position.

Young Earth Creationism
Age of Earth
This is the position that God created the world ~6000 years ago, though some may hold to 10000 or 20000 years. The age is that of the earth, the age of the universe is variable, but it was made at the same time at the earth and the universe's age is the same as the earth's age when measured by earth clocks. It denies the big bang occurred.

Species Change
Young Earth Creationism rejects the grand theory of evolution, the idea that all of life came from a single ancestor through a variety of creatures over millions of years. While some claim that it holds to the fixity of the species, this is a less helpful definition due to consensus on how species are defined. Fixity of the genera would be more accurate. It claims that God created various kinds or types of animals so there is no common ancestor of all creatures.

Noachic Deluge
Young Earth Creationism holds that the Flood of Noah was global and is the cause of sedimentary rocks and much fossilisation of plants and animals.

Old Earth Creationism
Age of Earth
This position thinks that the age of earth is 4 billion years and the universe several billion years older. It subscribes to an ancient cosmology including the big bang theory and stellar evolution.

Species Change
Old Earth Creationism also rejects the grand theory of evolution, though they think that various flora and fauna appeared on earth at various times over the last several million years. This are often ascribed to ongoing creative acts. Species may go extinct and fossils are dated according to evolutionary geological scales. Radio-dating is accepted as reliable.

Noachic Deluge
Old Earth Creationism states that the Flood of Noah was local, that the geological strata antedate the Flood by millions of years, and most fossilisation was not a result of the Flood.

Theistic Evolution
Age of Earth
This position thinks that the age of the earth and universe is billions of years. It holds to big bang theory and stellar evolution.

Species Change
Theistic Evolution thinks that all species arrives on this earth according to Darwin's General Theory of Evolution. All living things are linked by common ancestry. They deny the fixity of species, genera, orders etc. as new species are always evolving. Some hold to chemical evolution of life, others argue that the first cell was divinely created.

Noachic Deluge
Theistic Evolution holds no specific view on Noah's Flood. It may be mythical. If it occurred it was local at not responsible for sedimentary rocks or fossils. It denies that all land animals except those on the ark were destroyed. It may deny that all humans, except Noah's family died.

Summary
Young Earth Creationism and Old Earth Creationism deny the Grand Theory of Evolution, that is universal common descent is not a correct description of the history of life. Their differences concerning the appearance of life on earth leads to significant differences in theology however.

Old Earth Creationism and Theistic Evolution deny the earth is only several thousand years old. Both think that the universe is billions of years old, stellar evolution is correct and radio-dating is reliable

Intelligent Design
Intelligent Design does not fully fit into this scheme. It has been accused of being clandestine creationism. I am not certain this is fair as creationism is often meant to mean young earth creationism, and many advocates of intelligent design deny a young earth.

Intelligent design only has a position on biological evolution. It has no position on the age of the earth or Noah's Flood.

Intelligent design argues that features in living things that have the appearance of design have been designed by an intelligent designer. That is, design is real, not apparent. Their arguments include information content in the genome, irreducible complexity of biochemical pathways, and statistical impossibility of evolutionary required genomic changes.