When comparing Instagram Direct vs GroupMe, the Slant community recommends GroupMe for most people. In the question“What are the best messaging apps for Android?” GroupMe is ranked 23rd while Instagram Direct is ranked 47th. The most important reason people chose GroupMe is:
GroupMe has a built in function to read receipts.
Specs
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Pros
Pro Video & photo messages
Photos have to be cropped to be square.
Pro Filters
That can be applied to photos and videos.
Pro Group messages
With up to 15 people.

Pro Reads receipts
GroupMe has a built in function to read receipts.

Pro Great web client
GroupMe has an excellent web client that can be used to send and receive messages and manage groups from the desktop.

Pro IFTTT Integration
Allows sending messages from web services via IFTTT.

Pro Integrated calendar
It's possible to add location and time with reminders directly in the GroupMe app.

Pro Makes it easy to silence 1 or all groups
GroupMe has settings that allow muting a single group or turn off all GroupMe notifications from within the app.

Pro Does not require everyone in the group to have a smartphone
GroupMe can set up a custom phone number which allows people without the App to send and receive messages. This makes it easy to add anyone to messaging.
Cons
Con Walled garden
Can't communicate with people outside of Instagram.
Con Drains battery fast
GroupMe, in order to have a constant connection which allows for notifications drains the battery of a device quickly, which is not ideal for a messaging app that one needs on time notifications from.
