*こんな is an adjectival construction used as pre-noun, which indicates the type/kind (quality) of noun it is linked to. It can be translated as "such", "(...) like this or "this kind of" and it is used when talking about both something (abstract or concrete) or someone. ex. こんな家を見た事(は)ありますか。[konna ie o mita koto (wa) arimasuka ] "Have you ever seen a house like this?" こんな奴とは喋りたくない。very colloquial, talking to someone and showing some kind of intollerance to a third person. [konna yatsu to wa shaberitakunai!] "I don´t want to talk to such an a-hole!" (Please note that, despite 奴 is translated as "fellow" sometimes, it is a very derogatory term). (!) -When you are talking about something/someone who is far from the conversation, you are supposed to use あんな [anna] "like that(1)". -When the object/person is close to the listener, you are supposed to use そんな [sonna] "like that(2)". *こんなに is an adverbial construction used as pre-adjective, which indicates how much *quality adjective* something or someone is. It can be (roughly) translated as "so much/this much" 新幹線がこんなに早いと(は)思わなかった。[Shinkansen ga konnani hayai to (wa) omowanakatta] lit. "I did not think Shinkansen was so much fast" "I could´t imagine Shinkansen was this fast!" (Acrion: 新幹線がこんなに早く着くと(は)思わなかった。[Shinkansen ga konnani haiku tusk to wa omowanakatta] "I couln´t imagine THAT Shinkansen would arrive this early" (!) -When you are talking about something/someone who is far from the conversation, you are supposed to use あんなに [annani] "that much". -When the object/person is close to the listener, you are supposed to use そんなに [sonna] "like that(2)". LITTLE SUMMARY: こんな; あんな; そんな + noun = put emphasis on what KIND of object we are talking about. こんなに; あんなに; そんなに + adjective = underlines how much of a quality the object or the action we are talking about have.

こんな　　＝　このような (adjective) こんなに　＝　このように (adverb) It's the same difference as きれいな and きれいに。