Through is more like from one side to another, while throughout would be like "widespread" or "everywhere" within the defined area. We sometimes use "all through" to mean "throughout." For example, "When he was shot, the bullet passed right through his abdomen without hitting any major organs. However, he died from it later, as infection from the original wound spread throughout his body." , Thoroughly - (adverb.) 1. In a thorough manner; fully; entirely; completely, totally, absolutely..... for example: "I researched this issue thoroughly and still I couldn't find the problem" "I cleaned my body thoroughly after the mud fight" 2. Exhaustively complete: thoroughly searched. 3. Painstakingly accurate or careful: thoroughly researched. 4 Absolute; utter: It's been thoroughly pleasant. Thorough – (Adjective) 1. Executed without negligence or omissions: a thorough search. 2. Complete; perfect; utter: thorough enjoyment. 3. Extremely attentive to accuracy and detail; painstaking: athorough worker; a thorouh analysis. 4. Having full command or mastery of an art, talent, etc.: athorough actress. 5. Extending or passing through.

Come on, man, learn to use a dictionary!!!!