I tend to agree with LouLou, I don't think they are any different. I believe some of the issue could have been with getting approval from the FDA. They needed to try to eliminate things that may effect the delivery of the medication, to match what was done in the cayston trials. So they made the altera cosmetically different and for use only with Cayston. It also works out well for the two companies as they get sell more eflow units. In the price you pay for Cayston each month is included a new neb kit with head. Its not for our convenience, they are making money off including the new neb kit each month. With the Trio I get free with my Tobra prescription, I need to go 4 months before they send another one, and this gets much more use with 4 different meds per day.