These three tools are among the most-used on the whole site, and they are also among the most frequently confused with each other, because "do something with some of the pages in this PDF" describes all three at a glance. The actual difference is about what happens to the pages you are not focused on, and once that clicks, picking the right tool becomes automatic.
Delete Pages is the tool to reach for when most of a document is correct and a small number of specific pages need to go. You pick the pages to remove, and everything else stays together as one single file, in its original order, minus the pages you removed. This is the right choice for things like stripping a blank cover sheet, removing a page of internal notes before sending a document externally, or cutting out a duplicated page that got scanned twice by mistake. The defining trait: you end up with one file, slightly shorter than the original.
Extract Pages is the tool for when you need a specific, contiguous range of pages pulled out as their own standalone document, while everything about how those pages relate to each other is preserved. Think of it as "give me just pages 12 through 20 of this 40-page report, as their own 9-page file." This is the right call for pulling a single chapter out of a book-length PDF, isolating one exhibit from a larger legal filing, or grabbing just the results section out of a longer report to send separately. The defining trait: you end up with one new, smaller file representing a slice of the original.
Split Pages is the tool for when you want the entire document broken apart, either into every individual page as its own file, or into evenly-sized chunks, and you want all of those pieces handed back to you at once, bundled into a zip archive. This is the right call when you have a single 30-page scanned form that actually represents 30 separate, unrelated documents that got scanned together, or when a downstream system requires one PDF per page rather than one PDF containing many pages. The defining trait: you end up with many files, not one, delivered together as a zip.
A genuinely common mistake is reaching for Split when Extract was the actual need — someone wants "just the middle section" of a document, uses Split, gets back a zip file containing every individual page split apart, and then has to manually figure out which of those loose page files to keep and somehow reassemble them into one document again. Extract Pages does that entire job directly, in one step, without ever breaking the document down further than necessary.
A useful mental shortcut: if your goal sentence is "remove a few pages and keep the rest as one file," that is Delete Pages. If your goal sentence is "pull out this specific chunk as its own file," that is Extract Pages. If your goal sentence is "give me every page (or every chunk) as separate files," that is Split Pages. Getting this right on the first try, rather than the second, is worth the ten seconds it takes to actually think through which of those three sentences matches what you are trying to do.