flier / flyer 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. 👇
flier: (noun) someone who travels by air.
flyer: NA
flier: f·l·AY·er
flyer: f·l·AY·er
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)