Why do tab delimited files take less space than comma separated?

Question

I've noticed that the same data, stored in a tab separated file, seems to take less space than when that data is stored in a comma separated file.

My first thought was that tab characters take more space than comma characters, but everything I can find indicates they take the same amount of disk space in UTF/Ascii.

Answer 1

The CSV version probably has "quotes" around the data fields (just in case they contain commas themselves).