What is the difference between a command that ends with $-1-3$ and a command that ends with $-f1,3?$

The first specifies fields $1$ through $3$ and the second specifies fields $1$ and $3.$

There is no difference.

The first is a cut command and the second is a cat command.

The first specifies fields $1$ and $3$ and the second specifies fields $1$ through $3.$