Understand what the terms describe.
SMD describes surface-mount LED packages assembled onto a circuit board. COB describes chip-on-board construction, where LED chips are mounted directly on the substrate and covered by an encapsulating layer. These terms identify a construction approach; they do not establish a universal ranking for image quality, reliability or suitability.
Compare at the same operating conditions.
For an indoor meeting-room screen, examine pixel pitch, resolution, brightness at the intended setting, surface appearance, viewing angle and service method. Use the same source content and comparable brightness. If a supplier describes protective or visual advantages, ask for the applicable model data and test conditions rather than assuming that every COB or SMD product behaves the same.
Include practical ownership questions.
Ask how a faulty area is serviced, what parts are replaceable, what spares are supplied and how a replacement is matched to the display. Confirm the controller, calibration process and installation structure. For camera use, test the complete system with the real camera parameters; the packaging name alone is not a guarantee.