There are plenty of differences between the Bose soundbars; some are related to size and form factor, while others are related to expandability, features, and overall sound. The Bose Soundbars 300, 500, 700, and 900 are all expandable via Bose bass modules and satellite speakers, so their differences come more into play when considered as standalone units. Each successive soundbar in the line is wider than the last, with the 300 measuring 26.6 inches wide and the 900 measuring 45.5 inches wide. Only the Bose Smart Soundbar 900 features Dolby Atmos and Bose TrueSpace technology, which is key to remember if you’re looking for that level of immersive audio from a soundbar.