According to Diana Garland the definition of a companionship is one where the relationship partners seek to emphasize achieving deep intimacy with each other through individual growth and self-actualization and excellent communication sharing so that their emotional needs and personal goals can be met. She defines a partnership relationship as one that pursues greater purposes as the couple defines them in the will of God and so does not focus on itself but seeks to transcend itself. “In the companionship model,” she says, “authority and responsibility are to be divided; in partnership, they may take many different shapes depending on the context and tasks of the couple.” The latter “proposes no particular way of doing things but instead focuses on a vision and a purpose that go beyond the relationship itself.” So companionship emphasizes structure and process ..example boundaries , not the intention and content of the relationship as in the partnership model.
True partnership, however, can only grow from a base of equality between persons and a prerequisite establishment of companionship. How can there be heart-to-heart, open and free companionship if one is to submit with no choice in the matter or one has more loyalty to other, then other has to them? That road leads only to anger and depression and violence and some times even murder. Studies have consistently shown that wives in traditional marriages are much more depressed than men, unmarried women and working married women. Once this required base of egalitarian companionship is established, then the couple can go on to the greater shared mission and joint callings from God that is specific to that family.

Of those families that truly reach both companionship and partnership, my guess is that many may not stay there forever, depending on what is going on between them, what the shared family goals and tensions are at any particular moment. But when both are reached, and both stick around, oh, sweet Charity.

A Christian comparison of companionship or relationship vs partnership

(1) The word “relationship” describes what we are: A community of people bound together by our common life and blessings that we share together through our relationship with Christ.

(2) The word “partnership” describes how we are related to each other in that relationship: We are partners in an enterprise and calling in which we are to work together in a common purpose to obtain common objectives for the glory of God and the gospel of Jesus Christ (cf. Phil 1:27).

Partnership assumes basic notions of equality, mutuality
Companionship= fellowship . Fellowship means having or sharing with others certain things in common such as interest, goals, feelings, beliefs, activities, labor, privileges and responsibilities, experiences, and concerns.

(3) Fellowship can mean a partnership that involves working together and caring for one another as a company of people, like a company of soldiers or members of a family.

There are two main ideas with this word: (a) “to share together, take part together” in the sense of partnership or participation, and (b) “to share with” in the sense of giving to others.

Companionship is also the interchange or communication (communion) that exists among companions, those associated together through a relationship they hold in common. The key ingredient in companionship is communication. Key words that describe companionship are “interchange, communion, sharing.” Communication is the sharing of concepts, feelings, ideas, information, needs, etc. through words or other symbols like body language and actions so that all members of the relationship hold these things in common.

Distinction Between Relationship and Partnership.
Relationship describes what we are: a community of people bound together by our common life and blessings that we share together through our relationship with Christ. Partnership describes how we are related to each other in that relationship: we are partners in an enterprise and calling in which we are to work together in a common purpose to obtain common objectives for the glory of God and the gospel of Jesus Christ (cf. Phil 1:27).