I think you're imagining things... This spacing stuff is mostly defined in the font files and typst uses the same math font (or a more recent version, depending on your LaTeX config). I made a small comparison:
https://imgur.com/a/0k6dsok
Note that by default, typst uses the book weight from New Computer Modern. This corresponds to the default settings in LaTeX with the "fontsetup" package.
The only difference I can see is the spacing after the comma. Not sure why typst does it differently. I think typst might be doing the right thing here actually, but it's easy to adjust if you want.
You have a Mac with fractional scaling, your screenshots show the common blurriness render issue more than anything else I believe.
Apart from that there is clearly a size difference but I agree that it's quite close. I think it's good to be detailed oriented but I'm not sure the fetish around Latex rendering is warranted.
I think the size difference was just me being careless with zoom levels in different apps. I thought it was enough to make the point, since you can compare the space sizes to the character sizes. I put another comparison here: https://imgur.com/a/aZRx6fs , this time with same font size and zoom level.
Anyway I agree that looking exactly the same as Latex is not particularly desirable, but it helps for convincing Latex users to switch.
(The screenshots were made on Linux, with scaling but not fractional I think... But I can't check right now)
OK that must have been the screenshot software and zoom producing the blurriness.
In this new screenshot the rendering is perfect and one can't really tell any difference.
As for Latex I think it's a strong desire to belong to a special club that makes people use it and try to stick to the very specific look.
It does render math equation nicely, but the rest isn't anything special, especially compared to modern font/techniques.
I agree with you entirely fwliw. For me it's not a fetish particularly, the spacing just looks too wide in that one case and the comparisons if anything confirm that. "Too wide" is of course entirely a matter of personal opinion but I can't see myself switching to something I don't prefer the output of. I may well change my mind in future and I'm probably going to give typst a go at some point, because looking at the website there's a lot to like imo. Goodness knows for all that latex produces beautiful output it is a system with a lot of quirks and warts.
Sure, Latex gives a nice output but you have to suffer through a lot for that.
Look at the new screenshot, it's so close you can't really tell the difference without superposition.
In any case, Typst seem so much nicer to use that I think it's OK to let go of some minor details...
Could it be an illusion because the "zoom" is a bit different? (I was screenshotting different applications).
Here's a better comparison: 11pt size for both, then importing the LaTeX output in typst (using SVG conversion since typst cannot import PDF): https://imgur.com/a/aZRx6fs
I removed the "comma" that produced different spacing, and added the missing F_n. It seems there's still some different in spacing due to the quad.
If you still think the spacing around '+' is different you'll have to add some highlight/measurements or something to convince me, because they look quite identical to me...
Note that by default, typst uses the book weight from New Computer Modern. This corresponds to the default settings in LaTeX with the "fontsetup" package.
The only difference I can see is the spacing after the comma. Not sure why typst does it differently. I think typst might be doing the right thing here actually, but it's easy to adjust if you want.
My typst code:
My LaTeX code: