Critical missions – the thrust of the main story and each individual planet’s story – will be marked with different icons and will be the only missions shown by default. If you want to explore a planet in more depth, you can opt to see the Exploratory missions offered on every planet, with the planetary level sync ensuring that you never wind up too far above the planet’s power level. Heroic missions are also being restructured to two-person affairs available via a weekly console; check out the full diary for details.
Source: Official Site