Attachement is how much you like a person - you can be attached to someone you like or care about in many ways.

Examples -
I like my friends
I love my child
I love my significant other when I have one
I like my therapist

Transference is moving something from one place to another. Examples -

moving a lamp from a table to a stand - in therapy terms problem its dark need lamp solution move lamp closer.

moving food from the stove to the table - problem food too far awaysolution move it to table to be eaten

moving from one therapist to a new therapist

taking a problem from inside you and saying or telling the therapist what that problem is and working on solutions for that problem