What is the difference between a codified and uncodified constitution?

The difference between a codified and uncodified constitution is quite simple. Codified means the constitution is written down in a single document. The US constitution is codified. An uncodified constitution just measns it's not written down in one single document; the constitution could be found in many documents or even not written down- this is called a convention- where it's just tradition that gives a law it's power.