伊恩·比金对皮普的介绍如下:

pip was originally written to improve on easy_install in the following ways All packages are downloaded before installation. Partially-completed installation doesn’t occur as a result. Care is taken to present useful output on the console. The reasons for actions are kept track of. For instance, if a package is being installed, pip keeps track of why that package was required. Error messages should be useful. The code is relatively concise and cohesive, making it easier to use programmatically. Packages don’t have to be installed as egg archives, they can be installed flat (while keeping the egg metadata). Native support for other version control systems (Git, Mercurial and Bazaar) Uninstallation of packages. Simple to define fixed sets of requirements and reliably reproduce a set of packages.

这里的许多答案在2015年已经过时了(尽管丹尼尔·罗斯曼最初接受的答案并没有过时)。以下是目前的情况:

Binary packages are now distributed as wheels (.whl files)—not just on PyPI, but in third-party repositories like Christoph Gohlke's Extension Packages for Windows. pip can handle wheels; easy_install cannot. Virtual environments (which come built-in with 3.4, or can be added to 2.6+/3.1+ with virtualenv) have become a very important and prominent tool (and recommended in the official docs); they include pip out of the box, but don't even work properly with easy_install. The distribute package that included easy_install is no longer maintained. Its improvements over setuptools got merged back into setuptools. Trying to install distribute will just install setuptools instead. easy_install itself is only quasi-maintained. All of the cases where pip used to be inferior to easy_install—installing from an unpacked source tree, from a DVCS repo, etc.—are long-gone; you can pip install ., pip install git+https://. pip comes with the official Python 2.7 and 3.4+ packages from python.org, and a pip bootstrap is included by default if you build from source. The various incomplete bits of documentation on installing, using, and building packages have been replaced by the Python Packaging User Guide. Python's own documentation on Installing Python Modules now defers to this user guide, and explicitly calls out pip as "the preferred installer program". Other new features have been added to pip over the years that will never be in easy_install. For example, pip makes it easy to clone your site-packages by building a requirements file and then installing it with a single command on each side. Or to convert your requirements file to a local repo to use for in-house development. And so on.

The only good reason that I know of to use easy_install in 2015 is the special case of using Apple's pre-installed Python versions with OS X 10.5-10.8. Since 10.5, Apple has included easy_install, but as of 10.10 they still don't include pip. With 10.9+, you should still just use get-pip.py, but for 10.5-10.8, this has some problems, so it's easier to sudo easy_install pip. (In general, easy_install pip is a bad idea; it's only for OS X 10.5-10.8 that you want to do this.) Also, 10.5-10.8 include readline in a way that easy_install knows how to kludge around but pip doesn't, so you also want to sudo easy_install readline if you want to upgrade that.

只是遇到了一个特殊的情况，我必须使用easy_install而不是pip，或者我必须直接提取源代码。

对于GitPython包，pip中的版本太旧，为0.1.7，而easy_install中的版本是最新的，为0.3.2.rc1。

我使用的是Python 2.7.8。我不确定easy_install和pip的底层机制，但至少有些包的版本可能彼此不同，有时easy_install是版本较新的包。

easy_install GitPython

pip不会安装二进制包，并且在Windows上没有经过很好的测试。

由于Windows默认没有编译器，pip通常不能在那里使用。easy_install用于安装Windows的二进制包。

更新:正如一些人认为的那样，setuptools吸收了分发而不是其他方式。Setuptools是最新的，包含了最新的distutils更改和wheel格式。因此，easy_install和pip现在或多或少处于同等地位。

来源:http://pythonhosted.org/setuptools/merge-faq.html why-setuptools-and-not-distribute-or-another-name

偏爱pip的另一个尚未提及的原因是，它是新的热门词，在未来还会继续使用。

下面的信息图——摘自《打包指南v1.0》中的“打包的当前状态”一节——表明setuptools/easy_install在将来会消失。

下面是另一个来自distribute文档的信息图，显示Setuptools和easy_install将被新的hot - distribute和pip所取代。虽然pip仍然是新的热点，但在2013年，随着Setuptools v0.7的发布，Distribute与Setuptools合并了。