The latest version of Redis seems to be 4.0.2: https://redis.io/download
When I look up Redis in the Pip index it says it's at 2.10.6: https://pypi.python.org/pypi/redis
I'm new to Python package management and I don't understand the dependency here. Why are the versions so different?
Easy: 4.0.2 is the version of Redis, 2.10.6 is the version of the python library that wraps Redis. They are different things with two different release cycles. Major updates in the first may push the developers to release new versions of the latter in order to keep up with the new features, but there isn't a one-to-one relation between the two.
Just make sure that your redis-py client is compatible with your target Redis version.