Marketers deal with buyers.
It could be a business or a person but in the end, it is those who are paying for the product or service.
Content deals with audience.
An audience may or may not buy the product, but they are the perfect target for the message. Often the audience is an influencer either directly or indirectly they will amplify your message to the other people (who may or may not be the buyer of our products.)
In marketing funnel phases, buyer personas are engaged in the conversion phase while audience personas are involved in any phase-awareness, interest, desire, action.