Why there are 2 forms of template solutions in Phpcms

Why there are 2 kinds of template forms in Phpcms
Phpcms why there are 2 kinds of template forms such as: 1. There is a templates template under the Portal file directory. There is also a templates in the Modules module. Why? such as spend_list.html in the module template under the face of a spend_list.tpl.php everyone why is this? Just solve

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module, you can understand the cache file.
He is the product of combining the interface and the program, which is equivalent to the HTML PHP code you originally learned to write in PHP mixed.

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