Tons of improvements have been made in Drupal 2.x with regard to product workflows, UX and architecture. There’s also more functionality and features out of the box which makes it a lot easier to start a new commerce project.
The cool new installer makes it simple for any user to download and install Drupal commerce 2.x. You will be able to build all the components, put them together, generate some fancy composer news, etc.
Some terminologies have changed to make it more user-friendly, like instead of Nodes, they have two entity types – Product and Product variations. Payment methods are now called Payment gateways.
Features like Promotions and Coupons which were slightly buggy in version 1.x are now fixed – very usable and solid. In Commerce 1.x, the product architecture wasn’t very user-friendly. Adding products are much more structured now since the product variations handle the different attributes and variations of each product.