The different one for the bronchodilator was recommended for me by the Respiratory Therapist I saw. She said the location and severity of my BE, she thought this would be the best cup for the Bronchodilator. She primarily deals with cystic fibrosis patients who deal with a lot of mucus. Now I do not have cystic fibrosis but do produce 1/8-1/4 cup of mucus daily during my 3 nebbing sessions. And also the RT has over 35 years experience and was highly recommended by my Pulmonologist. As for the star cup, I was told the smaller the partical size the deeper it can get into the lungs.