The query is answered in STACK OVERFLOW.
Link: SAPUI5:: Difference between core:view and mvc:view - Stack Overflow
answer:
The View control is in sap.ui.core.mvc: see Class sap.ui.core.mvc.View in the API docu. Therefore, the namespace for a View element in an XML view definition is sap.ui.core.mvc.
This usually translates to something like:
<mvc:View xmlns:mvc="sap.ui.core.mvc" ... but of course the prefix is arbitrary and you could just as well have:
<banana:View xmlns:banana="sap.ui.core.mvc" ... The point is that it's the namespace that's important, at least technically. The confusion probably arises because the XML processor is rather lenient on the namespace specified for the root View element.
So to answer your question specifically, while core:View might be "correct" if you crazily specified xmlns:core="sap.ui.core.mvc", it would be very confusing, so the best way to express it is
<mvc:View xmlns:mvc="sap.ui.core.mvc" ...
