diCleaner, Finder, Disk Utility, and System Settings can show different storage numbers because they measure different concepts and scopes.
Logical and allocated size
A file has a logical length and occupies file-system blocks. Compression, sparse allocation, cloning, and block sharing can make physical usage different.
Packages
An item that looks like one file in Finder can be a directory containing many files. Applications and managed libraries are common examples.
Do not delete internal package items based only on a size scan.
Links and cloned data
Hard links, symbolic links, and copy-on-write clones can make totals appear duplicated or shared. Removing one path may not recover the sum of displayed logical sizes.
Purgeable storage and snapshots
macOS manages caches, local snapshots, and purgeable space separately. A file scanner may not classify these like System Settings.
Files changing during a scan
Mail, browsers, sync tools, virtual machines, and developer tools can change data continuously. Finish active tasks and rescan for a stable comparison.
Compare consistently
Compare the same volume, time, unit, and scope. Treat a result as an investigation aid rather than an exact accounting statement for every physical block.