From the official documentation:
Pylab combines the pyplot functionality (for plotting) with the numpy
functionality (for mathematics and for working with arrays) in a
single namespace, making that namespace (or environment) even more
MATLAB-like. For example, one can call the sin and cos functions just
like you could in MATLAB, as well as having all the features of
pyplot.
Note that pylab only imports from the top numpy namespace. Therefore, this will worK
import numpy
numpy.array # works
numpy.distutils # finds a module
And this will not
import pylab
pylab.array # works, is actually numpy array
pylab.distutils # gives an error