What are the main implications for each database option

Hello,

I know I can find full details on the extensive docs :-) but bottom line, what would be the main implications of each chosen database strategy?

I mean that it seems Ops Center can use a separate Oracle Database or sort of a "built-in" (or whatever it's called).
But, does this selection locks me in or can i switch between both of them anytime later?

What would be the main limitations of the "built-in"?

Thanks in advance,
Carlos.