Like well explained in the link below, an identifying relation is somewhat like a weak entity type relation to its parent in the ER conceptual model. UML style CADs for data modeling do not use ER symbols or concepts, and the kind of relations are: identifying, non-identifying and non-specific.
Identifying ones are relations parent/child where the child is kind of a weak entity (even at the traditional ER model its called identifying relationship), which does not have a real primary key by its own attributes and therefore cannot be identified uniquely by its own. Every access to the child table, on the physical model, will be dependent (inclusive semantically) on the parent's primary key, which turns into part or total of the child's primary key (also being a foreign key), generally resulting in a composite key on the child side. The eventual existing keys of the child itself are only pseudo or partial-keys, not sufficient to identify any instance of that type of Entity or Entity Set, without the parent's PK.
Non-identifying relationship are the ordinary relations (partial or total), of completely independent entity sets, whose instances do not depend on each others' primary keys to be uniquely identified, although they might need foreign keys for partial or total relationships, but not as the primary key of the child. The child has its own primary key. The parent idem. Both independently. Depending on the cardinality of the relationship, the PK of one goes as a FK to the other (N side), and if partial, can be null, if total, must be not null. But, at a relationship like this, the FK will never be also the PK of the child, as when an identifying relationship is the case.
http://docwiki.embarcadero.com/ERStudioDA/XE7/en/Creating_and_Editing_Relationships