What exactly is the difference? Is there any? My Zoi doesn’t have any special artistic traits that might influence that. Both let me choose which type of painting style I want and both raise the art skill level.
It maybe related to “mood” 
Oh, it’s not visible in my screenshot, but I just had the regular “fine” mood, so nothing special. And I think it usually shows the mood next to the action. Per example the “Singing in the Shower” has the green “Elated” moodlet standing right next to it. The “Paint with Soul” is always there, regardless of the mood, so I am not sure if it is mood related
Inspired mood is best for painting.
I know and thanks for that, but it still doesn’t exactly answer my question what the difference between the two actions is
Unlike the regular “Paint” option “Paint for Soul” focuses more on relaxation and self expression. Its primary purpose is not to make money but to improve your Zoi’s emotional well-being. If your Zoi is feeling stressed, sad, overwhelmed, or simply needs inspiration “Paint for Soul” is usually the better choice.
Ahh, thank you. I will pay attention to that next time. Do you know if it also influences Zois, that don’t have per se any artistic likes or affinities?
It does have an effect but it’s better for Zoi which have an “Artistic trait”. You can think of it like in Sims 3.
Gotcha. Thanks for the help. Shall I mark your reply as solution?
Yes it’s your choice.
But what’s interesting is that when I “painted with soul” — I almost always ended up with paintings of excellent quality that sold for good money. And with regular painting, every other painting ended up in the trash.
So “with soul” actually boosted my earnings 
Then maybe there is a different mechanic behind it?
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Well, perhaps they were entering into an “inspired state” right during the drawing process, and that’s why the paintings turned out better. I didn’t monitor this process, and I’m currently traveling to another city, so unfortunately I can’t log into the game and check.
You probably got confused about which topic you’re replying to? 
Ah i’m confused. Sorry 
@Minthyuyu I misinterpreted the wrong topic.
@Carnel ; "Middle school student and young adult shouldn’t be the same height." I was going to comment on the topic called
No worries, my brain made it so that you maybe just meant that not everything is logical in this game lol
I sincerely apologize for the “wrong topic comment”. @Minthyuyu @Carnel The “extreme summer heat” probably melted my brain.
We need to place 20 flags now. And 10 to make sure
The “Extreme Summer Heat” probably melted my brain. 
Sorry.