picky and choosy are the same. picky is more common in USA, I feel. pick and choose are synonyms (選擇，挑選） fastidious is not used often, but it usually means you're very concerned with details, very neat and clean. fussy means you "make a fuss"(抱怨) when you don't get your way. usually we say children are "fussy eaters", but in a formal situation you'd say picky or choosy. ,

Is this your homework? If so I suggest you consult www.thefreedictionary.com