Unlike most tuners, the Intellitouch does not use a microphone or cables to tune instruments.  It attaches to the headstock of your guitar (or on whatever instrument you use) and uses the vibration of the instrument to help tune your guitar, making this tuner ideal for use in a loud environment for trouble free tuning.  The Intellitouch has an easy to read LED screen that can be swiveled for easy viewing, or to be placed out of the way.  The PT-1 (unlike the lower model, PT-2) also features a back light for it's LED screen making the display easy to read in very low light, such as in many live gigs. The only other differences between the 2 models is the PT-1 also comes with a carrying case, and has the ability to "learn a tuning reference" from another instrument, which can be useful when playing along with instruments that cannot be tuned easily (such as a slightly off key accordion, or air organ).