The iPhone 8s looks like the iPhone 8– and the iPhone 7s, and the iPhone 7, and the iPhone 6s, and the iPhone 6! The iPhone X, the Xs, and the Xr also look a lot alike. How can you tell which phone you have?
In iOS 12, it’s easy. Just go to Settings / General / About… and there it is.
Note the name of your iPhone (at the top of the About screen) is up to you. Call your iPhone anything you want. If you don’t change it, your iPhone is just called “iPhone.” If you restored from the backup of an older iPhone when setting up this one, your new iPhone probably has the name of the older one. This will be confusing when you use AirDrop, when you look at Find My iPhone, and other times too, so it’s best to change the name to something that makes sense.
While you’re in there looking at your iPhone’s model name, you can also see your iPhone’s model number. You can tap the model number to see the Apple part number (it sure doesn’t look like something tappable, but it is.) This is, potentially, useful information too. So is your warranty expiration date, which for me is 8 days from the date of this post.
Note: if (because you’re on an older iOS) all you see in About is a model number, you can still figure out which iPhone you have by going to Apple’s page that lists all of the iPhones and model numbers, all the way back to the original iPhone of 2007, complete with pictures and specs. Worth a look.
Unfortunately Apple is not consistent with their nomenclature. The “Model Number” they show in Settings / General / About is called “Part Number” on their page listing the iPhone models. For example, in the picture above, the Model Number is listed as “MQ8X2LL/A,” but they really mean “Part number.” The actual model number for my iPhone, obtained by tapping where it says MQ8X2LL/A, is “A1897.” Now you know. They could fix this by changing the label in iOS 12’s About screen– maybe they will.