If asian and black noses are similar (low bridge, bulbous tip, wide nostrils), why are the results so drastically different?

There are many anatomical differences between Asian and Black patients. In particular the thickness of the skin on the tip of the nose is much thicker on Black patients and that cannot be modified with the Rhinoplasty. Other difference is Asian patients have a narrower nasal bone base, and a low radix, so an augmentation on the bridge of the nose has much better results, in Black patients the nasal bone base is wide, the bridge is very low and the results from a dorsal augmentation are less dramatic. Black patients tend to have an important alar flaring and thick nasal ala, that Asian patients usually do not have. Also there are other differences like the shape of the face, acne, etc.

With thick skin noses, whether black or southeast Asian, the skin thickness and technique used determine results.  In general these noses need structure added to the nose, such as rib graft or an implant.

Asian and African-American noses are completely different, therefore different techniques were used to make the appropriate changes to the nose yet give a natural result.  For many examples and more information, please see the video and the link below

Yes! You are correct for the most part. Asian noses and black noses have more structural similarities just as Indian noses and Caucasian noses are more similar. However, compared to Asian noses, black noses tend to be wider at the lower 1/3 and the skin is somewhat thicker skin. This may affect the final result at the nasal tip, but in general, the principles and techniques should be the same. Without seeing pictures of the rhinoplasty results you are referring to, another consideration is the patient's preference and desired end result. This may also affect the results you were viewing.

Some Asian and Black noses have similar characteristics but no two noses are exactly the same; skin thickness, width, and, projection will vary. You can find excellent results in patient of both ethnic backgrounds. . Consult with a rhinoplasty specialist who will discuss your goals and set reasonable expectations for you.