There are a number of variables regarding your question.
(1) Berkely has a large concentrated of significantly oldr 55+ communities
(2) The distance between the two is some 10 miles
(3) Berkely is more inland, while seaside is on the pennisula.
(4) One must consider when the last 10 year township assessment took place in each town.
Hope this helps.
Francesca Patrizio, Broker Sales Associate, ePro, SRES