Per Vaishnav Thelogy,
Vaikuntha is the Param Padam ('supreme abode'), or Paramapadam is the home of Supreme God Narayana or Vishnu which means Eternal Supreme Abode of infinite bliss without any anxiety and frustration of material world. It is an eternal abode of Supreme God Narayana or Vishnu or Hari, his consort Lakshmi, and Shesha, upon whom they rest.
Rig Veda (1.22.20) states, O? tad vi??o? paramam padam sada pasyanti suraya?: "All the suras (i.e., the devas) look towards the feet of Lord Vishnu as the Supreme Abode", referring to Vaikuntha, the Supreme Abode. Vaikuntha is considered by Vaishnavites to be the ultimate destination of souls who attain moksha or Liberation.
Vaikuntha is known as Paramdhama where liberated souls dwell for eternal period enjoying pure bliss and happiness in company of God Narayana or Vishnu. Vaikuntha is beyond the periphery of material universe and hence, can not be perceived or measured by material science and logics.
Ksheera Sagara or Ocean of milk is known to be the topmost realm in the material universe where Sheshashayee Lord Vishnu rests on Ananta Shesha. It is also sometimes known as local Vaikuntha of material universe which is approachable by devas or demigod in order to meet Lord Vishnu in case of any emergency or disturbance in universal balance. But, the original vaikuntha is beyond the material universe and is devoid of universal creation and annihilation which happens again & again.happens again & again.
Just wanted clarify the difference. In the show it Kheer Sagar not Vaikunth.
Not making any religious claims here just want to clarify again and try to remove any confusion.