I have to repeat what Govan said, but add to it.
With Drupal, if you really do not want to create your own modules and extensions, you really interact with the application. Even when you start using CCK, all you really do is switch radio buttons, fill out forms, and define new content options on the site.
Ruby on Rails are two things, and none of them have much in common with Drupal. You asked, โHow hard is that?โ To answer, you need to understand what Ruby and Rails are. Ruby is a programming language designed to make the life of a purist programmer easier and more enjoyable. So, the first part of how difficult it is to simply answer: "How long do you think you will need to learn a completely new programming language, such as PHP, but different."
Rails is a stubborn structure. He doubted that he describes how the Ruby web project should be structured, as well as providing several APIs for everything from database access to web presentation. To answer the question โhow difficult is itโ for Rails, then (assuming you know Ruby at this point), you should answer how much you need to know about caching, database design, page design, RESTful programming, etc.
This is not a short trip. you asked if there is a CCK equivalent for Ruby and Rails, which implies that at the moment your programming knowledge is somewhat limited. Ruby and Rails interact with the database. CCK allows you to define things in the database. Thus, with Ruby and Rails, you effectively bypass the wonderful dialogs and forms that CCK provides to you and does the bit of data definition yourself, in code.
From experience, when I hired experts in a different programming language and framework in my Rails teams, he took them from 1 to 3 months to get productivity, and from 3 to 6 months so that their performance started to increase and go to Rails experts in to my team.
Thus, in your particular case, I would not recommend switching from Drupal to Ruby on Rails.