gallop / galop 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. 👇
gallop: (noun) a fast gait of a horse; a two-beat stride during which all four legs are off the ground simultaneously. (verb) ride at a galloping pace. (verb) go at galloping speed. (verb) cause to move at full gallop.
galop: NA
gallop: g·AE·l·ah·p
galop: NA
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)