1. Alveoli are composed of epithelial layers and extracellular matrix enclosed in capillaries while alveolar sacs are the distal ends of alveolar ducts.
2. The alveoli sacs are formed by a group or cluster of alveoli, and it is there where they communicate while the alveoli are made up of collagen and elastic fibers.
3. The alveoli process the gases that the blood caries to the lungs expelling the carbon dioxide and letting the blood transport the oxygen to the cells in the body while it is in the alveolar sacs where this process takes place.
4. The word “alveolus” comes from the Latin word for “little cavity” while the term “alveolar sacs” is derived from the same word and is used to refer to the pouch where the alveoli are located