Which method is better for converting paper documents to PDF on iPhone: Note or Photos?

There isn’t a “better” here. It’s whatever works for you.

You’re making images (photos) of the paper, and storing those in different places; in images wrapped in a PDF file , or images in a Note, or images in Photos library or album will all work. Images in a Pages document would work too, and there are task-targeted third-party apps for receipts and other activities.

PDF files (whether containing text, or containing images as is the case here) can usually be directly passed around to others and across platforms, where Apple Notes documents cannot be as easily transferred.

None of these tools are particularly good at dealing with lots of scans, sorting, or storing them. (Using Photos app probably comes the closest, there.) That’s where third-party apps can work better.

Recent iOS versions can usually capture text from these images too, and purpose-built apps can also often provide that. As an example of this, Photos app has that scanning support integrated, meaning you can search for text in your photo library.

Using the Notes app on an iPhone or iPad is one of the fastest and easiest ways to scan multiple physical documents and convert them into a single PDF. The built-in document scanner in Notes allows you to quickly capture multiple pages, adjust their alignment, and save them as a single PDF file without needing third-party apps.

While many third-party apps offer additional features such as OCR (Optical Character Recognition) or cloud integration, some of them may require extra steps, such as exporting individual pages and manually combining them later using another app. This can make the process more time-consuming compared to the streamlined experience provided by the Notes app.

moshang wrote:

I understand the ways to making my paper document into pdf file by many ways from multiple guides. But, I'm not sure which one is better.

Have you tried doing it with both Notes and Photos? Which method did you find easier or had better results? What further processing do you expect to do with the pdf's you create.