I did not know there was a difference between primary and secondary keywords and I thought that it was just generally considered as keywords in its entirety and therefore there was no differentiation however from what you have said here it does seem that there is a distinct difference between the two of them and how they can actually help the website to grow.keywords on your content can be broadly categorized into two types, primary keywords and secondary keywords. Primary keywords are the main keywords that you are using on your content. Primary keywords describe what your article is about. Secondary keywords are the keywords related to primary keywords but less important keywords on your content. If you are writing about iOS device, iphone can be your primary content. However android or windows devices can be secondary keywords.