Thank you for your replyI think Busan lately have done alot more to develop its skyline compare to seoul,seoul needs to do alot more effort to maintain its title.
Seoul has the height limits according to the district to protect the cultural heritages or airforce flight while Busan has much freer of regulations or restrictions.
That's why Seoul has not many tall buildings over 250m.
For example, this central area of Seoul is 150m of height limit to protect UNESCO cultural heritage.
credits to: blog.paran.com/imck