I asked https://health.stackexchange.com/q/146/43 and I see that I received one close vote saying the question is off-topic. Are terminology questions on-topic?
Asking what the difference is seems like a biology question to me and not related to health and hence off topic. If the question related to something a doctor said or something a person read about a health issue, then I think it would be on topic. This, however, seems like a subtle and silly distinction.