What's the difference between porn and nudes?

Everyone's entitled to their own opinion, I'd like to say. I'm not telling y'all what to do with your relationship! But anyhow...my husband and I agreed to no porn when we started dating. We both watched it. He was the one who suggested it, not me, actually! He said it felt dirty to look at other women naked when he loved me so much. I know most, ahem, ALL, women would be mad if some dude was receiving nudes. Even if the woman was a country away! So my question is - why do people think porn is okay but nudes from strangers aren't? I know nudes are more personal. But at the end of the day a naked woman is a naked woman. Not trying to cause a fight, just legitimately curious!