What's the difference between CMs "push" method (Ansible) to "pull" method (Chef/Puppet)?

I know that some of the advantages of Ansible over many other CMs are these: 1. Ansible's scripts being written in YAML, a simple serialization language. 1. The fact that one doesn't have to install it on the machines you deploy its commands/playbooks. 1. Ansible's strong user base and community (for example, galaxy-roles) I know there is another bold different, using the "push" method" instead of some other CMs using the "pull" method. What is the difference here? Maybe it reflects difference 2?