What's the difference between an autoresponder and transactional message?

Some Tatango customers confuse autoresponders with the Transactional Gateway, as they're very similar in function. The difference between the two is that an autoresponder message is initiated by a customer texting an autoresponder keyword to your short code, while with the Transactional Gateway, a message is initiated by a customer entering their mobile phone number into a website or point of sale system.