"conceit" is the best defined as a lengthy or extended

Not really, 

1.
excessive pride in oneself."he was puffed up with conceit"synonyms:vanity, narcissism, conceitedness, egotism, self-admiration, self-regard; Moreantonyms:humility2.a fanciful expression in writing or speech; an elaborate metaphor."the idea of the wind's singing is a prime romantic conceit"synonyms:image, imagery, metaphor, simile, trope; Morean artistic effect or device."the director's brilliant conceit was to film this tale in black and white"a fanciful notion."he is alarmed by the widespread conceit that he spent most of the 1980s drunk"synonyms:idea, notion, fancy"the conceit of time travel"

The major difference is that a histogram is only used to plot the frequency of score occurrences in a continuous data set that has been divided into classes, called bins.  bar charts, on the other hand, can be used for a great deal of other types ofvariables  including  ordinal  andnominal  data sets.