OK, Atheists, you can take a day off. This one is about a family feud.
Young Earth Creationism essentially says that Genesis is correct as written and best interpreted merely as it is written. God made the heavens and the earth in an ordinary calendar week about 6,000 years ago. No Big Bang, no billions of years, no evolution. Adam and Eve and the Fall were real, as were Noah and the Flood.
Old Earth Creationism says that Big Bang is how God made the universe, and evolution (or something like it) is how he made life over the past 13 billion years. No DAYS of Creation. Probably no actual Adam and Eve. And no flood of Noah- or if so a small, local flood which we will CALL “universal” and swear we are not being sarcastic.
Old Earth Creationists start with modern science (and secular interpretations) and reinterpret the Bible accordingly. Young Earth Creationists start with the Bible and use it to understand modern science, both in terms of understanding observations, but also which interpretations to accept or reject.
In a nutshell:
Young Earth Creationists say the world, nature, and man are corrupted and put their trust in the Bible.
Old Earth Creationists say the Bible is corrupt and put their faith in the world, nature, and man.
Debates are like a nose: When you pick a side, consider what it is you are actually picking.
For more on this topic, check out the Confessions of a Young Earth Creationist Series.
And remember, #JesusLovesYou