Difference between CI 2 and Ci3 ? (Newbie learning from old books)

Iam a newbie in Codeigniter.

Does CI 2 and CI 3 have "breaking" differences like laravel 4 and laravel 5.( method names , folder structure)

iam about to start learning CI 3


i dont have books based on CI 3 but i have collection of books based on CI 2. 

Is learning from CI 2 books to learn CI 3 will end up like laravel learning?