is a macro package to isolate Emacs configuration lines in the init file. By isolating related lines, the configuration performs better and is easier to maintain.
use-package is the name of a package and the name of a macro that it provides. This macro is used in the init-file to configure packages using deferred and delayed loading to speed the start up of Emacs.
use-package also consolidates configuration steps before and after loading a package. It is also used to consolidate key-bindings to minimize overlaps and conflicts.