grate / great are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
grate: (noun) a frame of iron bars to hold a fire. (noun) a harsh rasping sound made by scraping something. (noun) a barrier that has parallel or crossed bars blocking a passage but admitting air. (verb) furnish with a grate. (verb) reduce to small shreds or pulverize by rubbing against a rough or sharp perforated surface. (verb) make a grating or grinding sound by rubbing together.
great: (noun) a person who has achieved distinction and honor in some field. (adjective) relatively large in size or number or extent; larger than others of its kind. (adjective) of major significance or importance. (adjective) remarkable or out of the ordinary in degree or magnitude or effect.
grate: g·r·EY·t
great: g·r·EY·t
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)