Which planner?

Ground Control Software Other GCS
1

I am new to quadcopter and just purchased my first quadcopter kit and flight controller “APM 2.8 ArduPilot Flight Controller & 6M GPS 433Mhz Telemetry Power Module”. I have not received my items yet, but though I would pre-install the software needed as I seen from several youtube videos and came to this site to download the planner software, but I am abit confuse what the difference in the Mission Planner & the
APM Planner 2.0. Which one should I download?

2

Try both and see which you like best.
If you are past the 1990s and not stuck with windows, then APM planner is the only multiplatform option. Generally more stable and reliable, but less bells and whistles.