If you look at the design principles in the first commit compared to the current version, you will notice that while there have been some additions and tweaks, the core principles remain pretty much intact:

• Agentless: Everything should be managed by the SSH daemon, the WinRM protocol in the case of Windows machines, or API calls—there should be no reliance on either custom agents or additional ports that need to be opened or interacted with on the target host
• Minimal: You should be able to manage new remote machines without having to install any new software as each Linux host will typically have at least SSH and Python installed as part of a minimal installation
• Descriptive: You should be able to describe your infrastructure, stack, or task in a language that is readable by both machines and humans
• Simple: The setup processes and learning curve should be simple and feel intuitive
• Easy to use: It should be the easiest IT automation system to use, ever

A few of these principles make Ansible quite different to other tools. Let's take a look at the most basic difference between Ansible and other tools, such as Puppet and Chef.