A complete guide to Ruby on Rails — MVC architecture, directory structure, RESTful and nested routing, ActiveRecord queries and associations, validations and callbacks, ActionController with filters and strong parameters, ActionView helpers and partials, ActionMailer, ActiveJob, ActionCable, Concerns, Service Objects, Form Objects, encrypted credentials, and production deployment.
A complete guide to Sinatra — classic and modular applications, routing with parameters and conditions, requests and responses, ERB and Haml templates, before/after filters, helpers, sessions, Rack middleware, Sinatra::Base for larger apps, modular multi-file structure, ActiveRecord integration, JSON APIs, testing with Rack::Test, deployment, and a Sinatra vs Rails comparison.