What is the difference between 'USB CDC' and 'USB HID'?

[LHAEU]

• I'm using STM32F072VB.
• ​I want to communicate with 'USB' instead of 'Serial'.
• Should i use ​'USB CDC(VCP)'? or Should i use 'USB HID'?
• I ​created a 'USB HID' test code with CubeMX and checked it. ( Reference Image1)

​<Image1>

1. ​Can i do 'download communication' with 'USB HID'? (*download communication: write function of boot loader... etc...)
2. What is the difference between 'USB CDC' and 'USB HID'?