There is a huge difference. When we interact in person, we are building a mutual relationship. Your friend may tell you about their new job, but may chose to adjust the tone and information to be more sensitive to the layoff you just experienced. Online, you get unidirectional bragging that needs to be as engaging and exaggerated as possible to get promoted by the algorithm. Their new job becomes the pinnacle of a lifetime of stellar achievement. If people interacted in person like they do on social media, the rest of us would avoid them like a contagious rash.
You only see the good online for the most part. In person, when they tell you about the amazing vacation, you hear about how their kid cried all the way on the 6 hour flight and how the wife got sick while over there. When they tell you about the new job, they also tell you how even though it is going great, they don't know about their new coworker that is being really annoying.
Online is 99% the good stuff (or the controversial stuff), in real life it is more nuanced and complex. I saw a bunch of relatives recently that I hadn't seen in about 4 years. I have 2 cousins that have kids that I see in pictures playing together all the time, and it makes me happy, but a bit guilty because my only child was born at a time where there are no cousins around his age. Turns out there's a bunch of stress in the relationship because the two groups of kids fight more than play.
Another cousin stayed in the corner, because he's a major MAGA guy and didn't want to interact with the more liberal rest of the group, obvious from his Facebook posts. Except that isn't the case at all, he's actually still divorcing his wife I thought he divorced 4 years ago, fighting a custody battle, and dealing with an injury where his company doesn't believe is worth him being off work for. Again, nuance and complexity adds humanity.
After reading The Last Psychiatrist's _Sadly, Porn_ I'd say that it's the performative nature of social media. In the social media environment you're reading projected images -- performances designed to appeal to the infinite audience of the platform. When you interact with someone in real life, there's an authentic communication between two people. You at least have the chance to really connect, ask questions, and have a real human conversation.
The in person conversations are much less likely to be embellished and polished to look like more than they are. The in person conversations are also a form of two-way communication, rather than something more like a person standing on the street corner shouting into a megaphone to catch the attention of anyone nearby. The human interaction makes a world of difference.
Also the in person conversations are probably spread out. They'd typically not all happen within the span of a couple of minutes, not giving you time to process and work through each emotion.
Unless you're at a party or something, and a lot of people do find parties overwhelming.
You're meeting a friend in an hour, so you enjoy your moment for a while before you see them
You spend time with a friend and are happy for them. After you bump into your coworker and chat for 20 mins about politics. Interesting, but you disagree. But you have lunch with a neighbour soon, so off you trot to go see their holiday pictures. All looks lovely yada yada yada - 1 even after the other, can being digested with context. Time is taken to enjoy or question certain things.
You are enjoying your moment for 1 minute. You open your phone and scroll facebook. You see all of that within 1 viewport. You haven't enjoyed your moment for long - you haven't enjoyed other's success cos you're still kinda angry about the political post etc.
IMO It's all about your mindset. You can look at a travel photo that your friend took and depending on your mindset, you're either going to feel jealous and wishing you could do the same or feel happy for that person.
You meet your friend, he tells you about his new job, you congratulate him.
You meet your coworker and chat to him about politics, and it's kinda interesting.
You meet your neighbor after their trip and they show you the photos and you're fascinated.
You meet your cousin in real life, you see he looks better, you compliment him. You don't feel like you need to do something yourself.
What is it about doing it online that hurts?