As for tech specs, smart POS terminals may:
Have 1 or 2 touchscreens. If there are two, one of them would typically be customer-facing.
Have a physical keypad, or use the screen for PIN entry (PIN on glass) and signatures.
Accept contactless, chip and swipe cards.
Have an inbuilt camera for barcode scanning and more.
Function through WiFi, 4G or 3G.
Have an inbuilt receipt printer.
Be portable, stationary or both. Some smart terminals from the same manufacturer can even be synced, as in the case of Clover POS by First Data.