For ford vehicles why is there sub models like XLT XL etc. Are those related to Trim levels?

I'm trying to know more regarding the Submodels for Ford Vehicles I'm confused with XL, XLT lauriat, if they are related to the trims or the vehicle package

Submodel=trim=package. All the same thing.

http://www.quickquote.ford.com/2014-Ford-F-150?lang=en&redirectpage=Bp2ChooseYourPath&branding=1&fmccmp=lp-trucks-top-bp-f-150

Thanks for the answers