C6H5COCH2Cl is Phenacyl chloride or 2-chloro acetophenone its commonly used as a riot control agent and is designated as CN (tear gas ==>a group of substances that irritate the mucous membranes of the eyes, causing a stinging sensation and tears.)
C6H4ClCOCH3 ==> the molecular formula is same as phenacyl chloride but this can be isomers . For example 4-Chloroacetophenone (structural isomers )