Reacting to jump scares. In real life I twitch a little, in the game my head should have snapped off with how fast my head snaps to staring at the sky.

It might sound intentionally controversial but sex is harder in games than it is. ^
Feelings and emotions are easier to express in real life, as most games have no option for this.
The game itself can be a way to express emotions anyway and then a game is an easier medium than acting in the material world.

There aren't many games where one can write a post like here, forum is a nice mix of reality and game.

Not participating, just here for the snark. Do Razer products still come with utterly cancerous software that should be considered a compubiological hazard?

Cooking.

Say that you wanted to make a grilled cheese in real life. You go to the store and buy some bread, cheese and cooking spray. Spray your waffle or panini maker with spray, put cheese between bread, press it for a few minutes, take it out and eat.

In a video game, if you want to make grilled cheese, you still need the bread and cheese, only to make the cheese, you need some milk that only drops 5% of the time from Mad Cows on level 5 of the Chaos Dungeon. And, oh, you also need a Cooking skill of at least 20, so you have to make approximately seven hundred omelettes and plates of spaghetti Carbonara before you get the necessary skills to make your grilled cheese. And even then, your attempt to make the grilled cheese will probably fail half of the time even though it should by all rights be the easiest thing to cook in the world.

Driving in games is harder than in most non racing games. Try driving correctly with only the arrow buttons on your keyboard. If you know how to drive in real live, it's easier not to crash into something than in a game.

Crafting. In games, it is way harder/tedious to get the required materials you need to craft a specific item you (the player) wants.

In real life, you can go to the store and buy the required materials to craft/make what you want.

In games you either have to grind for those same materials or outright buy them, but sometimes merchants won't have the last thing you need, which means you have to grind them anyway.

Cooking.... In real life I can defend myself pretty well but ingame it's normally a nightmare... not just only having to murder millions of mobs just for an ingredient, but also with tedious minigames for doing a simple omelette XD

Going where you want to go. I've never run into invisible walls in real life. In real life, I am capable of crossing low hedges, small streams and even bushes and a forest, without pre-defined paths. Also, when necessary I can apply force to open most doors. There are hardly any doors that are purely decorative and most windows (and even walls) are destructible.

Talking to random people is also harder in computer games than in real life. In real life, you sometimes get strange looks if you talk to random strangers. In many games you simply can't. Or all random strangers say the same single line.

But the big hard thing in games is: picking up stuff. In real life, I can pick up every flower pot, every random stone (as long as it's not too big). In games, your selection is limited to those objects that are defined as interactive. Even worse: in 3D adventures you have to stand pixel perfect on the correct spot to interact with anything. I never had to walk back and forth and shimmy side to side in real live to find that small sweet spot from which I can pick up my coffee. Thank goodness!

Picking something up and putting it down again in the place you want to - looking at you Skyrim

Stacking things one on top of another...

It's harder not to find reason to help a random stranger out.

I would say there are a few things harder to do in games than in real life:
1) wearing multiple jewelries:
In videogames you are limited to 2 rings 1 necklace. Common your character has 10 fingers. Also a necklace doesn't weight so much that you couldn't wear 2 or more of them. Why can't I wear the 5 rings that I want and the 2 necklaces? Sooo frustrating
2) Destroying a wooden post: (looking at you GTA)
You can destroy steel posts no problem barely scratching your car but you see that wooden post? that's a no no. Crash into it and your car goes flying back but the post doesn't have any scratches.
3) Destroying buildings.
In most games you can shoot a bazooka at a building you can shoot flaming arrows at wooden or straw buildings, you can shoot tank shells at a building and the building does not have any scratches. In real life by doing all that the building would be destroyed. I guess the buildings in games are secretly nuclear shelter

In my opinion, there are not many things to do that is currently harder to do in games. But to 'replicate' the realism of real life is currently one of them. Of course companies are making big progress especially in visual department. But the feeling of wind on your face, smell of earth after a rain, feeling of hunger or pain - 'enjoying' those things is harder in games.

Driving while following the road rules!
Try staying in the correct lane, and following the speed limit they said. It'll be fun they said.

GTA logic: Who needs a road!

As others have said, stepping over something like a small fence can be impossible in a game.

To give something a bit more interesting, though, I'm going to say walking, since it's the user that is affected in both real life and game world. I have no problem spending half an hour walking to and from the shops in real life, and will rarely run. In a game, though, I'm more likely to manage to climb over that small fence than I am to just walk the whole way.