“Handlebars” is a nickname for a fancy mustache. This pretty well embodies how Handlebars.js is a superset of the Mustache template library. Superset means that it has all the features of Mustache plus some extras. Like Mustache, Handlebars is a logicless template library. If you use a logicless template system after using tools like ASP or PHP you may feel there is a lot missing. It takes a little adjusting to, and one nice thing about Handlebars vs Mustache is that it makes the transition a little easier and more graceful.
By the way, this is one part of a 5 piece series, so if you want to explore other options, don’t forget to visit the series start where I explain the biases and summary information and link to all of the tutorials.