To know and to understand

Listening to Pimsleur i discovered that apparently
(B"I don't know"   =   "$B$o$+$j$^$;$s(B"
(B"I don't understand"   =   "$B$o$+$j$^$;$s(B"
(B
(BWhat i wonder is how to distinuish between those two 
(Bmeanings if (when?) they come to colide in the sentence.
(BLet's engineer a sentence here:
(B"I don't know and i don't understand".
(BI have trouble believeing it would be:
(B"$BJ,$+$j$^$;$s!!$H!!J,$+$j$^$;$s(B".
(B
(BHow is that solved in Japanese? The example in the file was
(B-"$B$9$_$^$;$s!"$R$S$dF;M}$O!!$I$3$G$9$+(B?"
(B-"$BJ,$+$j$^$;$s(B."
(BHow does the questioner know that the questionee:
(Ba) understood the question but didn't know the answer
(Balternatively
(Bb) didn't understand the question
(B?
(B
(B
(B-- 
(B
(BKindly
(BKonrad
(B---------------------------------------------------
(BMay all spammers die an agonizing death; have no burial places; 
(Btheir souls be chased by demons in Gehenna from one room to 
(Banother for all eternity and more.
(B
(BSleep - thing used by ineffective people
(B            as a substitute for coffee
(B
(BAmbition - a poor excuse for not having
(B                 enough sense to be lazy
(B---------------------------------------------------