Sidekiq Rails 4.2使用活动作业还是工作者？有什么不同

This is my first processing jobs asynchronously I am implementing Sidekiq for background processing in my app. I will use it for reminder emails and in-app notifications. I am confused as to whether I should use Active Job to create a job that sends an email or a Sidekiq Worker to send an email. They seem to do the same thing and Rails 4.2 Active Job seems very new…is it replacing the need for a Sidekiq Worker? This is my first processing jobs asynchronously