The "Missions" tab has hourly, daily and weekly tasks (e.g. gather resources, open crates, defeat scientists). Completed missions give scrap and season pass XP – hourly 30 XP, daily 100 XP, weekly 400 XP.
The "Achievements" tab holds about 80 achievements with several tiers. Many unlock a chat title you can select there. Achievements and titles are kept across wipes.
Comfort: you can re-roll your daily missions once a day, pin up to 3 missions to the HUD, and a mission streak brings extra rewards. The tab also shows today's XP sources and how rare an achievement is.