Grails vs Play

Grails is an abstraction over Spring and Hibernate. This makes Grails applications fast and scalable. This is because both Spring and Hibernate are themselves scalable.

Grails is a full-stack web framework, not just MVC. It contains a lot of stuff out of the box, but it doesn’t enforce it. It contains over 900 plugins which provide a Groovy API for a lot of useful and well-known Java libraries. And what is more important is that they are super easy to install!

Setting up a new project is quite fast and code generation (scaffolding) saves you a lot of time. It also uses a convention over configuration principle which helps you bypass all the configuration trouble.

Grails also comes with a reloading mechanism out of the box.

Grails is designed to be a rapid development framework with a straight learning curve. It advocates convention over configuration. Extensibility is very simple when using plugins (there is a lot of them). One command in the console – and all the dependencies and configurations are managed for you.

Do you need something advanced in the UI? You can either create it in GSP with an addon of CSS/JavaScript or you can find a plugin that will do the work for you. Plugins include integration with Bootstrap, jQuery, Yeoman and much more.

The Documentation section is actually a wiki, which can be modified by any logged in user. It has an official manual, tutorials, screencasts, a sample app and much more. If that does not do it for you, then there are countless third-party tutorials, more than 12k questions on SO and much much more

Play has quite a large community which provides numerous tutorials and videos related to developing with Play.
The Play official documentation covers many things, such as the framework itself but also specific stuff such as Akka, SBT and Netty.

There are also many big companies that base their main sites around Play, one of them is LinkedIn which provides third-party documentation on a regular basis.

Play framework's convention over configuration methodology makes most Play projects have a very similar structure. This means that the code written for the framework is very readable. This enables a developer to switch between applications without having to relearn the ecosystem for every project. The built-in templating system also helps with code and makes it possible to have a very low count of lines of code.

Play is very simple to get started. The documentation is very helpful for beginners and advanced users alike and the official website has a great "Getting Started" tutorial to begin developing with Play.

Play Framework is asynchronous from the bottom up: asynchronous is default in Play API.

Play uses Akka for concurrency, Scala for a templating engine, Netty as a client-server framework and SBT (Simple Build Tool) for building. And they all come out of the box.
Play also comes with the option to scaffold your applications. Play is an all-embracing ecosystem designed to increase developer productivity and shorten development times.