Since we've gone over this repeatedly, and many here still aren't sure what the difference is, here are some examples from a recent discussion on Quora (the answers are from Laura Hancock, with a 'chronic addition to fiction and diction'.
Telling: When I got to the airport, he was happy to see me.
Showing: When I got to the airport, his face broke open into a big smile.
In the "showing" sentence, I don't have to tell you that he's happy. He's smiling. If he wasn't happy to see me, he'd likely not be smiling. You know he's smiling.
Telling: She had beautiful long brown hair.
Showing: Her hair cascaded over her shoulders in glorious, sandy waves.
In the "showing" sentence, the hair in question is clearly not short. The adjective "glorious" is hyperbolic, but clearly positive. I mean, while I didn't use the direct words "long" and "beautiful," you don't think I'm describing somebody with short, unkempt hair, do you? And if I say "sandy," you know I mean "a brownish blond." I'm not describing a redhead or somebody with black hair, and unless I added additional pertinent information, I likely don't mean there is literal sand in her hair.
The "showing" sentences are more evocative. They allow me to inject images into your mind rather than simply describing facts to you.
Now, this doesn't mean that 'telling' is bad all the time, mind you. Sometimes telling is good, particularly if the detail in question is relatively unimportant.
"When I saw her for the first time, she was wearing a green dress; the expression on her face said that she was about to chew lead and spit bullets."
I told you that she was wearing a green dress. That detail was relatively unimportant (but added since I may plan to do something with that detail later). I showed you that she was… probably not happy. The more evocative phrase in that sentence is "chew lead and spit bullets."
Let's switch it up.
"When I saw her for the first time she was absolutely furious; adorned in a gown greener than grass, an organza flurry scurried in her wake."
I told you she was furious. I showed you that the dress was a dark, lush green, and likely a fancy dress since I call it a "gown" and I reference organza, which is typically used in evening wear and it's long enough to "flurry in her wake." A casual sundress won't do that. Plus, the word "adorned" implies "carefully decorated." You don't "adorn" yourself for any average Tuesday. You "adorn" yourself for your wedding day.
Basically, the only bad part of the "show don't tell" advice is that it doesn't address the reality that… uh, sometimes you need to tell. Otherwise you're just going to get convoluted.
In the example where I call it a mere "green dress," that detail isn't important at the moment. It may become important later.
"It was in that moment I realized that the dress had clearly been picked to match her eyes."
Now the fact that the dress is green is important because I use it to describe her eyes, which are clearly also green. But it's not important at the moment. Here's a put-together scene:
When I saw her for the first time, she was wearing a green dress; the expression on her face said that she was about to chew lead and spit bullets. Wonderful.
She glared up at me; the crown of her head couldn't have reached my chin, but the fury made her ten feet tall. "I can't believe you have the nerve to show your fool face here," she hissed.
It was in that moment I realized the dress had clearly been picked to match her eyes. Probably to accentuate them.
Or maybe it was merely the unmitigated fury making them stand out like that.
Again. The green isn't important at first. But it becomes important. I told you, and then I showed you.