What is the difference in potency between codeine and morphine?

Alot: Codeine to be effective needs to be converted to Morphine in your body. Some lack the ability to do that efficiently and consequently have poor analgesia and more side effects from Codeine. Generally, codeine is about 1/10 as effective as Morphine but for some even less effective.

Morphine: Morphine is much more potent as compared with codeine .