For iPhone and iPad users, text messages appear almost identical (and both take place in the "Messages" app), but they're actually very different.
Text messages are sent between phone numbers, so they require cellular towers.
When you send a text message on an iPhone or iPad, it shows up in green.
While you can send and receive text messages with an eSIM, it means you'll need to leave your Primary SIM "on" so your phone number remains active (and carrier charges may apply).
If you attempt to send text messages with your Primary SIM "off," you may see a message like "You were unable to send a text message due to a device restriction."
iMessages are sent over an internet connection (Wi-Fi or data).
iMessage is a free messaging service only available for iOS devices (iPhones and iPads), and the messages are sent from one Apple ID to another Apple ID (but you can also configure it to use your phone number).
When you send an iMessage on an iPhone or iPad, it shows up in blue.
If you have an iPhone or iPad, it's easy to set up iMessage for eSIM, so it works perfectly over your new eSIM data plan.
While iMessages can work using your Apple ID or your phone number, text messages can ONLY work using your phone number.