Philatelic Covers

Event Cover - a cover, usually with a cachet, marking an event. Examples of event covers include: first flight covers, airport dedication covers, and stamp show covers.

First Day Cover - a cover cancelled on the day a stamp is issued, in the city in which it is released. Modern First Day Covers may actually be cancelled up to 30 days after the date of issue, and not necessarily in the city whose postmarks they bear. First Day Covers may be addressed or unaddressed, and with or without cachets. See also Unofficial First Day Cover and Second Day Cover.

Philatelic - pertaining to the hobby of collecting stamps, postal stationery, postal history, and related materials.

Philatelic Cover - a cover that is philatelic in origin, as opposed to a cover produced in the normal course of commercial or personal correspondence.

Source: A Glossary of Terms for the Collector of United States Stamps (glossary.usstamps.org/)
When I began collecting my sole focus was on stamps; however, after a hiatus of about two decades, my collecting interest has broadened to include not only postal history but also philatelic covers.

Here are a few examples of the types mentioned in the U.S. Stamp Society's glossary:

Air Mail Rate Change - 1928


Stamp Show - 2011


First Day Cover - 2004