Why are there stars on some currency and not on others? Are they worth more?

Answer 1

The stars on some of the currency behind the serial number indicate that the bill was printed erroneously the first time and had to be destroyed. This could be for a variety of reasons, such as being printed off center or some other defect. When this occurs, the bill is reprinted, and the reprinted bill is printed with the star behind it. They generally aren't worth more unless you have one that is really old. That is worth a little more, but not a whole lot more.

Answer 2

Star Notes:
When an imperfect note is detected during the manufacturing process after the serial number has been overprinted, it must be replaced with a new note. A "star" note is used to replace the imperfect note. Reusing that exact serial number to replace the imperfect note is costly and time consuming. The "star" note has its own special serial number followed by a star in place of a suffix letter.

The serial number of the imperfect note that was removed is not used again in the same numbering sequence.

Star notes do have modest collector value. Some collectors even specialize in star notes.