부끄럽다-> shy, embarrassed, ashamed, shameful

당황스럽다-> taken aback, flustered

Ex) 난 너무 부끄러워= I am so embarrassed

난 너무 당황스럽다= I am so taken aback

부끄럽다 - to be embarrassed or ashamed 당황스럽다 - to be flustered or frustrated