Dynamic Audiences are ever-growing sets of contacts that are grouped together based on certain criteria. Contacts can enter and leave the audience based on whether they meet the criteria. For example, if the dynamic audience is 'Vendors with MA status of proposal sent' then when the audience is created, it would populate with all vendors who have the MA status of proposal sent. As time goes on, if any of the vendors in this audience change their MA status, they will leave the audience. On the contrary, any vendors who have an MA sent to them and their status changed to 'Proposal Sent', they will enter the audience.
Static Audiences are also a set of contacts which follow certain criteria, however the contacts in this audience will never leave and no new contacts will enter. It is static and will never change.
Audiences - What's the Difference Between a Dynamic Audience and a Static Audience?
