On iPhone and iPad, the “Messages” app combines both features. The classic Text message is shown in green, an iMessage is highlighted in blue.
An SMS is sent as common via the mobile network. An imessage for windows message is sent on the internet.
An SMS can be received by every cellular phone owner. An iMessage can only be sent to owners of Mac pc, iPhone, iPad and iPod touch.
Your iOS device automatically detects if the recipient can get an iMessage. If this is not the case, a classic Text message will be directed.
Whether you send out an iMessage or an Text message, you constantly see in the written text field (see picture).