For those who have the same question and still have a little confusion, This may help them.
1.Infrastructure: As the definition says one part of Infrastructure is a bridge between domain classes( consists of business-related logic) and Database relationship. and if you are using ORM (Like Hibernate Spring data e.t.c)then the implementation is already there. the whole conceptionconcept is about decoupling.
2.Core: Thanks to the accepted answer it has already described the core part beautifully. I would prefer to put Value Objects inside the core, Being said that
Core is the building blocks not specific to any domain or technology, containing generic building blocks like lists, case classes, and actors.
it is pointing towards value Objects and may be custom types.