* Teensy has a native USB, much faster than the USB/serial bridge of an Arduino. I also find the discrete transaction nature of USB easier for communication, though good old fashioned serial is easier for many people to integrate on the host side.
* Arduino has analog inputs, the chip in Teensy does not. If you need analog you can either add an analog converter chip, or go ghetto and use a digital pin, a resistor, and a capacitor and time how long it takes to recharge after you flush the charge. Drawbacks abound.
* Arduino is a complete environment tailored to easy uptake. This is the most important point of Arduino. You can take someone who does not know what a compiler is, and in minutes they can be in control of hardware. The brilliance of Arduino does not show in the bullet list, it is brilliance by omission.
* Teensy has a native USB, much faster than the USB/serial bridge of an Arduino. I also find the discrete transaction nature of USB easier for communication, though good old fashioned serial is easier for many people to integrate on the host side.
* Arduino has analog inputs, the chip in Teensy does not. If you need analog you can either add an analog converter chip, or go ghetto and use a digital pin, a resistor, and a capacitor and time how long it takes to recharge after you flush the charge. Drawbacks abound.
* Arduino is a complete environment tailored to easy uptake. This is the most important point of Arduino. You can take someone who does not know what a compiler is, and in minutes they can be in control of hardware. The brilliance of Arduino does not show in the bullet list, it is brilliance by omission.