Innocence is the lack of knowledge - very childlike 

Ignorance is the lack of capacity to absorb knowledge - whether intentional or not 

Innocence is not knowing about some mature topic, usually with a negative or inappropriate connotation. The innocent admit to this lack of knowledge, and they typically either ask for the information or have no problem staying in their bubble of innocence. They do not pretend they understand and do not argue whatever point they wish without any prior knowledge. They do not take their innocence and harm others with it.

Ignorance is not knowing about some mature topic and then proceeding to talk on or argue over that topic. The ignorant refuse to admit their lack of knowledge. They instead pretend that they have done the thinking and research on the topic, and they attack those who actually have. They act as if there could never be an opinion besides theirs, and they refuse to accept facts that contradict their own opinion. 

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