Your title is what is on your business card.
It's how you present yourself to people outside the company, to explain what you are to those who may not understand the specifics of your industry. It almost never changes over the course of your stay with an employer but may change over the course of your career. For example, you can be "Programmer" for 10 years and then decide on a career change and take a job as "Project Manager" in another company.
Your role is what you actually do on a project.
It is internal to the company and specific to each project you are assigned to. Roles are linked to job descriptions listing associated responsibilities and behaviours, and those around you will know what they can expect from you.They are not linked to pay grades and do not affect salary or benefits. Like theatre roles, they change with each project based on your expertise vs what is needed. For example: "Lead Programmer" on one project and "AI Programmer" on another (see more on Leads and how they should change for each project in tomorrow's post).
Your grade determines pay scale.
It is a representation of how experienced you are in your position. It is a relative value, relevant only to your company because different company use different scales to measure competency. Your grade is first assigned when you join the company and changes with each promotion you get. If your company uses job descriptions, your grade means that you meet specific targets in terms of behaviour and skill documented there.
And when all that's said and done, the best way to earn respect is still to stand up and do the thing that needs doing, regardless of title, role or grade.