In this case, it will create Rails application "apps" with latest version installed on our machine.
If you want to create Rails application for specific rails versions, use below command
rails _x.x.x_ <appn...
./script/generate model mymodelname
creates an activerecord model that is usually linked to a database but doesn't have to be.
./script/generate scaffold scaffoldname
creates a model, a controller, a layout, some css styles etc. This gives you the model plus everything else...