I don't think this has been highlighted here yet....
An email today from Jetstar indicates that Starclass will be replaced from May 21st with 'Business Class' and 'Business Class Max'. Business Class Max costs $200 extra and includes entry to airport lounges and bonus frequent flyer points. 'Business Class' passengers can still access lounges but now will have to pay to enter (they don't indicate what the entry charge will be).
Previously with StarClass you were entitled to 'free' lounge access. Existing StarClass bookings will maintain the old privileges i.e inclusive of entry to lounges.
There is no difference between Business and Business Max seats - they are the same as StarClass was.