Some trouble using the template

[zenyanbo]

Hello, I'm having trouble using the template. I don't quite understand how the api and templates work. For example, I enabled role: system, assistant, user and the corresponding format ### System, ### Assistant, ### User in yaml.
roles:
assistant: '### Assistant:'
system: '### System:'
user: '### User:'

So how do templates work? I guess ### System, ### Assistant, ### User are all in {{.Input}} or other variables SystemPrompt, Input, Instruction, content, Functions. Right?

In addition, I can't find the difference between these variables, SystemPrompt and Instruction, Input and content, etc.