Designation means a distinguishing name or title, whereas position indicates where someone is relative to some hierarchy,in any collection of people who have been grouped together in some sort of industry etc.
What is a role in a job?
A "job role" is a description of what a person does. A "job title" is a convenient name for a role. For example: At my last job, my role was to write code that helped us be sure that our product worked as well as we thought it did.
What is the difference between a job title and job description?
A job title is essentially the name of a position within an organization filled by an employee. Job function is the routine set of tasks or activities undertaken by a person in that position. An employee's title and function are often closely related, though not all job functions are clear based on title alone.