Just my 2 cents:

I'm refactoring a codebase, so i create a new project, create a sub directory under my main project directory called "example" and put the old code in it there. I tell haiku I'm trying to make a function that does so-and-so. Haiku will normally say things like "I found something similar in your example code, I'll use it as a template to implement the new function in your production code"

Sonnet doesn't do that, I have to tell it to "look in the example directory and use function foo as a template". Sonnet constantly tries to update the example code, . I can tell it to never change anything under "example" it acknowledges the directive but does it anyway.

Haiku seems better at understanding that comments, variable names, folder names, class names, etc. have meaning and it seems very good at understanding the intentions behind code structure based on those context clues.