Ruby on Rails VS Django
Rails is not dissing Django, they can co-exist as brothers.
Ruby on Rails VS PHP
The above is not a fair comparison because it is matching a framework versus a language but still funny to watch if you have worked in at least one of those two technologies. There are more videos between those two here, there and over here.
Ruby on Rails VS Java
The point in the above for Java is that different components have to be put together from other sources whereas for Rails, it is all in one box. I love the jars(Java .jar files), spring(Spring Framework), the beans(JavaBeans), tapestry(Apache Tapestry) and the teddy bear who usually hibernates(Hibernate, an ORM for Java). Hilarious and witty way of putting the above together.