On Google Fi, Messages can sync messages with web app. I wish there was a Messages for iOS for reading Google Fi messages on my iPad. But that would be a pretty niche use and they would have to call it something less confusing.
Hangouts used to have the ability to do both Hangouts and SMS. But it didn't have the ability to automatically switch like iMessage. They could have also rolled out the ability to sync SMS to more carriers instead of just Sprint and Google Fi.
Hangouts is dead, replaced by Google Chat.
On Google Fi, Messages can sync messages with web app. I wish there was a Messages for iOS for reading Google Fi messages on my iPad. But that would be a pretty niche use and they would have to call it something less confusing.
Hangouts used to have the ability to do both Hangouts and SMS. But it didn't have the ability to automatically switch like iMessage. They could have also rolled out the ability to sync SMS to more carriers instead of just Sprint and Google Fi.