The vocabulary. If you understand vocabulary but not grammar, you can still communicate. If you only know grammar and not vocabulary, however, you will not be able to effectively communicate. To...
Informative language is language targeted to you. For example; We want you to buy this product, and you will have the time of your life with this product.
Be more specific - there are dozens and dozens of designs of piston engine, designed for different fuels, speeds, uses, etc etc , in total they will have thousands upon thousands of components.