The B-21 more than likely will have two very advanced LPI AESA arrays, 360 deg coverage passive peripheral arrays, no active countermeasures (chaff/flares), no AINS (star tracker) and will more than likely have some dorsal mounted antennas, all these will all be more advanced than the B-2 I assume. Whats interesting are the cylindrical (looks to be) upper and lower pop-out antennas, they don't seem to be for flight test only. Plus what other magical tech we may not know about for a very long time. The other thing is the unique OML LO surface texture and treatments, this is really different compared to other LO platforms, 30+ years of LO evolution post-B-2, I assume adopted from the "RQ-180".