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What do you mean by that? Is it the quality of the tutorial or the how the concepts were explained?
For me Processing and p5.js are quite similar in a sense that they offer both a similar API (set of functions) to draw, process, display and interact with the user / other types of hardware.
The big difference is that p5.js is web based which means that you have access to the whole Web ecosystem which includes: JavaScript (the programming language), browser APIs, HTML / CSS, online APIs and services, NPM packages, Typescript, front-end frameworks (React, Vue, Svelte…) and so much more (3D, fonts, animation, network…).
On the other hand Processing was made using Java so you can use libraries that are more “low level” and close to the actual hardware you are running on. You can also use powerful libraries and the Java ecosystem for building applications.
For design and generative art it doesn’t really make a difference except if you are doing performance intensive work / advanced 3D visualization…
Here is an example of creative coding sketches I made using both Processing and p5.js (you can find both versions of the sketches) without too much trouble:
As a final word, I would personally go for p5.js because the web is so much flexible and rich when it comes to design and interactivity.