I am having trouble finding the answer to this question also. The answers I have read so far all seem to be partial/incomplete answers.
Just as the OP stated, when sending a text, and you get to the screen where you select the recipient(s) that you will be sending the text to... if you choose more than 1 person, then a little option bar appears that says:
"Recipients Reply To: ○Group ○MMS ○Just Me"
and then you have to choose 1 of those 3 options that are given. Now, I haven't yet seen a clear and specific answer about exactly what each option is, ESPECIALLY the description and differences of the "Group" and "MMS" options.
Someone please help!
’Group’ uses features and functionality specific to the Verizon Messages+ App, so its best to use when all participants are also using that app.
‘MMS’ uses standard multimedia messaging protocols so its best to use when messaging a group across different networks, apps and device types.