Ideograms are used to write the thing or the idea represented by their drawing. 
Sois used for writing the word ``bull'', and, the slate of a scribe, is used for writing the word ``scribe.'' As Egyptian doesn't use space between the words, and doesn't write vowels, this writing would have been very ambiguous, if it hadn't used determinatives. These are signs used as a word-ending, to specify the semantic category of a word. For example, the signs read ``iew''. But that might be the verb ``to lament'', or the substantives ``dog'' or ``wrongdoing''. So three different determinatives are used: , which designates any action of the mouth, for dogs, and , a sign used for small and evil things alike. So the word  means ``to lament,'' whereas  means ``dog'' and  means ``wrongdoing''.   See the disucssion of the word  henu