Factory hard reset will reset your phone to factory settings. Hard reset will clear a forgotten pass code. The reset will remove all data, including photos, contacts, texts, etc. WILL NOT REMOVE APPLE ID - ICLOUD
Factory reset is done if you have access to the settings, and does the same thing. ressets the phone to factory settings.
What is Activation Lock (apple lock/ iCloud lock)? https://www.youtube.com/watch?v=Un6862_lGsQ
Check Activation Lock (Apple / iCloud lock) status instructions: https://www.youtube.com/edit?o=U&video_id=KNyKMwNoqyw