Finishers and Garnishes are covers added to the headlights and tail lights to change the outline and look of the car slightly. Terminology in the United States is fractured and confused, so you have a number of options. "headlight trim", "eyelids", "headlight surround". Finishers seem to be more accepted of a term in England. These parts are not often found in the United States.

http://www.geocities.jp/aw73gou/fit/diy/doov_garnish.htm (for the japanese "finisher")

http://www.rhdjapan.com/abflug-headlight-finisher-inner-beze... (finishers in English)

This isn't a widely accepted term in the United States though. These parts are usually not legal, and not often used. the closest item is the "eyelids" which are smaller covers. These are just as illegal, but are more commonly used.

http://eos.meccahosting.com/~a0001eeb/bodykits_miscellaneous... (eyelids)

In a way, there is no specific equivalent. Since honda's accessory catalog uses "taillight garnish" I'm putting forth that term as my suggestion.

http://www.bernardiparts.com/Honda-Tail-Light-Garnish-Ridgel...