Quest objectives completed - get_quest

can someone explain what objectives_completed mean? is there any way to have objectives_completed and completed differ? i think the purpose of objective completed is that if the quest have more objectives to let us know which one is completed and which not based on the servername .

622": {
“completed”: false,
“name”: “Proof of Strength 2 (Thief)”,
“npc”: [
“objectives_completed”: false,
“servername”: “QNO_SD_GU_019”,
“type”: 16,