What is the difference between these two buttons?

To$...$

Select one:

There is no difference.

The To field will have the e$-$mail addresses of one or more recipients, the email addresses in the CC field are added for them to get the information in the e$-$mail.

The To field will have the e$-$mail address of only the first recipient, the CC field will have the e$-$mail address of the next recipient.

The To field will have the e$-$mail addresses of one or more recipients, the e$-$mail address in the CC field will be hidden from everyone else.