Hi, Thanks for asking. Bronchitis is inflammation of air way tubes large & medium sized- which lead to mucus production, cough & short breath due to less air entry in lungs. While Emphysema is weakening of air sacs ( alveoli- in which smallest branch of bronchial tree opens up & makes fresh air available for blood purification )- these sacs break up to create bigger air spaces in lung.. thus lessening the available exposure area for gaseous exchange & purification of blood. * Thus though causes are different there is shortness of breath due to less oxygenation of blood. Hope that clears up the doubt. Thanks.