Busy is a VERB. (Action) = To be very involved in an activity or many activities. Examples : I am busy. You are busy. He was busy. She will be busy... etc. Busily is an ADVERB (Describing word) telling HOW someone was doing / in what way. Examples: I seemsed hurried, busily cleaning my desk. (HOW did I clean it?) Yep, you got it now... :)

Im sorry its sinonim. Words having the same meaning.

Busy is having no time, doing something important. Busily mabye it's a sinonym of quickly

Whoo hoo! Party! Thanks.

The busy body was busily doing busybody things! :P