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
Short answer is they are the same thing. ActiveJob calls it a Job whereas Sidekiq calls it a Worker. I've decided to keep the terminology different so that people can distinguish the two.
You can use either one. Note that ActiveJob does not provide access to the full set of Sidekiq options so if you want to customize options for your job you might need to make it a Worker.