Google Groups is a service created by Google in 2001 based on the archives of the old Usenet service. It is a way to send emails to a predefined list of email addresses. Each email address must either be a Gmail address or one that has been associated with a Google Account. The product has not been improved since its original launch, and does not provide any collaboration tools besides group email.
Joinable provides other integrated tools: calendar, file sharing, and polling to name a few
Joinable provides a central location for all your group needs Including your contact list, messages, a group calendar which syncs to Google Calendar, simple and event polling, interactive group maps and a shared folder for files, photos, and links. Google Groups is an email service focused purely on group communications, both inside and outside of work.
Joinable messaging goes beyond email, to text messaging and beautiful native mobile apps
Easily send messages to everyone, track who has opened and read your messages, and send quick reminders to the ones who haven’t. Google Groups is only for gmail users.
Joinable is free of charge and doesn't show advertising
Joinable's basic product is free of charge, now and always, and has no distracting advertising. Google Groups is free for individuals but has a monthly membership fee for businesses.
Strict privacy controls
Each group is a private communication hub, where your members control precisely what they share and with whom. Google Groups has some privacy measures dependent on the group.