Use motion if the DB follows the reciever it is man coverage, If he moves anywhere else beside following the reciever it is a zone ( Moves in when u motion out or backs off etc)
Cover 2 the saftys will always be evenly spread in the secondary
Cover 3 one safty will usually move toward the middle of the field us a snap count to make sure dont just hike quick at the line
Man most of the time saftys will be spread evenly
( READ PACKAGES AS WELL IF THEY ARE IN ONE SAFTY SETS PAY ATTENTION USE YOUR MOTION READING D IS VERY IMPORTANT SET YOUR AUDIBLES TO BEAT EACH ZONE AND HAVE A MAN BURNER)
Hope this helps