Learning: View Templates
There are two main types of templates, node and system templates
A node template is when a node in the system is being viewed – ie. a part of the site structure.
A system template is used when accessing functionality within the system. The main difference between system and node templates are what variables you can access and what override rules can be used. In system templates, there will be specific variables associated with the functionality being used that you wouldn’t access via a node template.