答案很简单:您的python环境使用不同的路径.做

The answer is pretty easy: your python environment is using different paths. do

$ which pip
$ sudo which pip

您将获得两条不同的路径.

and you'll get two different paths.

认真考虑改用python virtualenv，这样可以更好地控制您.

Seriously consider changing over to use python virtualenv, which gets you lots better control.