Pairs often confused
tandis que or alors que in French?
Both contrast, and tandis que is more written; alors que also keeps a TIME sense that tandis que has nearly lost.
Why
In a synthesis, tandis que sets two documents side by side without ambiguity. Alors que does the same, but the sentence can also read "at the moment when", and context decides. When the contrast must be sharp, tandis que is safer.
tandis que
Le premier texte insiste sur le coût, tandis que le second parle d'efficacité.
The first text stresses cost, while the second speaks of effectiveness.
alors que
Il est arrivé alors que la séance commençait.
He arrived just as the session was starting.