In frame-based processing, blocks process data one frame at a time. Each frame of data contains sequential samples from an independent channel. For more information, see Sample- and Frame-Based Concepts in the DSP System Toolbox™ documentation.
In sample-based processing, blocks process signals one sample at a time. Each element of the input signal represents one sample of a distinct channel. For more information, see What Is Sample-Based Processing? in the DSP System Toolbox documentation.