Digital Signal Processing (DSP) differs from microprocessor-based devices primarily in its focus on processing signals rather than general computation. MOSFETs are preferred in high-speed applications due to their faster switching capabilities and lower current draw compared to BJTs, although at very high speeds, MOSFETs can consume more power due to input capacitance and transition currents. The discussion highlights that while DSP and microprocessors may utilize similar transistor technologies, the distinction lies in their application rather than the underlying technology. The importance of understanding the current draw versus switching speed in CMOS and BJT ICs is emphasized. Overall, the conversation underscores the need for foundational knowledge in electronics to engage meaningfully in discussions about these technologies.