Concordances, dictionaries and thesauri are all related tools, each with the purpose of helping the linguist to select the correct term. They are also unique, each providing valuable assistance to the linguist in its own way.
Concordances do not attempt to define words, but instead show the word as used in a variety of sentences. This allows the user to see the different ways a word is used, allowing them to determine if it is also correct for the context of the file they are translating.
Dictionaries were initially born of concordances, from which experts determined the various uses of each word as they appeared in context, and described each of these uses under the word. Now with this resource, we can quickly determine the various meanings of a word to see if it is indeed correct for our purposes.
The English language is not very tolerant of repeated words, even if they do have the correct meaning, which is where thesauri come in. For example you cannot say that something is located locally, or that the connector is connected. It is better to select a different word with a similar meaning to avoid this type of problem. Thesauri provide a collection of synonyms, and sometimes antonyms for each usage of a particular word. This can make writing more interesting and expressive, especially when a word is on the tip of one’s tongue.
In their individual ways, these three tools can be very valuable to those who craft language, whether they be writers, translators or proofreaders. It is beneficial to use all three wherever possible.