using nodes or make new entities? [duplicate]

Question

I'm wondering why we use entities for some cases, when we can use nodes. When we use nodes we can use lots of modules to use for almost any purpose.. The above sentence is my main question, while I was planning to make an election system. Here is my case: I want to write a simple voting system that users become candidates, then an admin authenticate them, then for a period of time othef users come and vote to number of candidates(number of candidates is defined by admin) The structure I planned is to make outside of drupal world is to have three tables 1. A table for elections, containing information about the election itself for example election for choosing manager this year! 2. A table for candidates containing election reference( no 1 ), user id , accepted status, and votes. 3. A table for keep track of election containing the voter id, and candidate id , and election id. I was thinking these can be fields of nodes, that we only work with these values by php codes in template for example. But I want to make a drupal module. But I'm confused that what is the best DRUPAL WAY to do that? Thanks