Could anyone help me to clarify the difference between ', or' and 'or'? Sometimes I see articles are intentionally written this way rather than just reflex. I've made examples below, and explained by myself.
'Or' case
- That system is the circulatory system, or the cardiovascular system
→ In this case, ', or' suggests that both 'the circulatory system' and 'cardiovascular system' are the same thing, but have different names
- That system is the circulatory system or the cardiovascular system
→ In this case, 'or' suggests that 'the circulatory system' and 'cardiovascular system' are two different things, and that 'that system' I am talking about can be either of 'cardiovascular' or 'circulatory'.