I didn't see anyone saying their job was better than anyone else's, just defending their own job. "Makes a difference" is not the same as "changes the world," and so I would think your job as an RN definitely makes a difference. Even if your primary reason is to earn money, if you've ever helped relieve someone's pain you've made a difference.
I think most jobs do make a difference. I live in a farming area and we would surely all starve if it wasn't for the farmers, truck drivers, distributers, meat packers, railroad workers, and Walmart cashiers that get the food from the ground to us.
Lawyers and bankers are vital when we need them and yes, artists, musicians and dog show workers, all make a difference, adding beauty and pleasure to the world.
I was finding the conversation interesting. The only person who sounded judgey to me was you, of us.