SMS or text messages use your mobile connection, which bounces from one cell tower to another. For iMessages, it’s Apple’s service for messaging that comes with every iPad and iPhone. iMessages transfer information via the internet. So, you’ll need WiFi or cellular data to send messages to another iPhone/iPad. However, you can utilize any cell reception to send text messages. When you’re using an iPhone, the only reason to use SMS is when you’re talking to someone who isn’t using an Apple device. You also use this when you don’t have any data on your smart device.