Answer: Depending on the specific synonym you use, your sentence can have a different connotation, tone, and mood. These all change the meaning of the sentence.
Explanation: For example, if you write the sentence-
>She is flying in the air.
and instead change it to-
>She is fluttering in the air.
This changes the tone and meaning of the sentence from a girl possibly flying in an airplane, to a girl flying like a fairy with wings. The tone also changes from monotone to graceful and whimsical. Both words mean the same thing, but change the meaning of the sentence.
