Primary and Secondary Source
Primary and secondary sources are almost the same but different. This is what I have learnt from Secondary sources.
Primary sources is the original source of information. It could be a diary, manuscript, recording, etc. Primary sources is usually is more important the Secondary sources.
Secondary sources is the after story. It's what happens after what you have already heard from the Primary sources. Secondary gets the information from the primary sources, A book, textbook, website, etc.