These are different types of connections to the NBN. According to their page, AGL uses 6 different types.
They relate to how the connection gets to you. For exmaple Fibre to the premises (sometimes called Fibre to the Home or FTTH) connects straight to your property.
AGL have a good summary of the types: https://www.agl.com.au/help-support/internet-mobile/network-and-coverages/nbn-connection-types