"The threefold dharma"

The metaphor in "The threefold dharma" which arises is the image of an ocean, air in between the sky, and the Sun. The sun is the Buddha; his light emanates from the picture, the light of wisdom, shining the truth. The air, which penetrates all: the Sun, the sky, and the ocean, is the Dhamma. The air is the most invisible, untouchable element of all, yet it penetrates the whole picture. The ocean is the Sangha; the waves of the ocean are the members of the monastic Sangha. The members of the ideal Sangha would be the ones who entered a different depth of ocean - arahant would touch the biggest depth of the ocean. A certain amount of members of the monastic Sangha would also belong to the ideal Sangha, or those who entered the stream of awakening. Although it is not part of the image, it is common knowledge that rivers will sooner or later find their way to the ocean, and that parallel is relevant to all beings, as we all will meet the ocean; it is inevitable. The ocean, air and Sun are interdependent parts of the image. The most invisible element, the air, representing the Dharma, has the most subtle, untold and unseen element of love, compassion and grace with it--grace which Buddhists rarely, if ever, talk about because one can hardly describe it.

Taking refuge 

Taking refuge implies commitment towards the object/body/subject/idea onto which the refuge is taken. There might not be any predetermined formula for what happens to an individual person when they take refuge, as each one's level of commitment, understanding and thirst for truth/ liberation differs greatly. Usually, a person who takes refuge should feel a sense of security which they realise they were previously lacking.

There is a difference between going to Buddha for guidance and for refuge. Firstly, we might differentiate the meaning of the word "Buddha". It can be in reference to historical Gautama Buddha, or it can reference Buddha's enlightened qualities of wisdom, discernment and compassion. Going to the Buddha for guidance would imply an intention to learn from Buddha's teaching of wisdom and compassion. Going to Buddha for refuge would imply surrendering one's sense of security and safety for Buddha's enlightening qualities.
There are two types of Sangha: one which is monastic, and another which is ideal. Taking refuge within monastic Sangha requires proper ordination into a Buddhist order. For example, Theravada Buddhists would need to first be novices before being able to accept a "robe", with different levels of ordinations belonging to women and men within this lineage. Taking refuge in ideal Sangha means taking refuge in anyone who has attained the first level of enlightenment (the one who will return seven times). Members of ideal Sangha do not need to be ordained as monks or nuns, and not all nuns and monks belong to ideal Sangha. Sangha is in both cases a certain community, whereas teachings are delivered through scriptures. Taking refuge in monastic Sangha can bring a certain sense of belonging, whereas taking refuge in teachings would bring a sense of responsibility for one's own inquiry and path to enlightenment. Taking refuge in Sangha does not necessarily take the responsibility away; however, it could cause reliance on other members of Sangha. Also, taking refuge in monastic Sangha requires one's submission to monastic rules which are outwardly written, whereas taking refuge in teaching requires understanding of the teachings and of its subtle aspects which might not necessarily be written.
Taking refuge in Buddha can have more abstract qualities and can be inferred as taking refuge in Buddha's nature, which anyone can attain. 

Taking refuge in another being is different because this other being might not necessarily represent these qualities of Buddha which are symbols of our own potential

Reference:

9 .E., 2020: Discussion: Taking Refuge . [online] courses.edx. Available at: <https://www.edx.org/course/buddhism-through-its-scriptures> [Accessed 2 April 2020].