The B in the product name denotes Buffer. In particular deep buffers:
Deep buffer Technology Cisco Catalyst 9300 higher scale models have a deeper buffer to address the requirements of rich multi-media lossless content delivery and large routing tables in a fixed access solution with a wide range of uplink choices for deployment flexibility.
Here the real difference between them.
Stackable 24 10/100/1000 Mbps UPOE ports; PoE budget of 830W with 1100 WAC power supply; supports StackWise-480 and StackPower.
Stackable 24 10/100/1000 Mbps UPOE ports that provide deep buffers and higher scale; PoE budget of 830W with 1100 WAC power supply; supports StackWise-480 and StackPower.