Commitment - Wedding - Marriage - Legal Marriage
What's in a Word?

Commitment Ceremony

A ceremony that acknowledges your commitment to one another but does not create a legally recognised change in your status

Wedding

A wedding refers to the events of a day (in some cultures this might stretch to several days). It  generally includes a ceremony to unite a couple for life and a celebratory event in which family and friends of the couple join them for a meal  and other activities such as cutting a cake, toasts, dancing, etc.  There is no reason, legally or otherwise, why  couples who cannot legally marry shouldn't have a wedding.

Marriage

Marriage, as they say, lasts a lifetime, so the word describes a condition or status which can only be dissolved by the death of one of the parties or by a court. But the word can also be used to describe an event. Typically on wedding invitations guests are invited to "the marriage of" and this is understood to be the marriage ceremony. Where there is a reception afterwards, that information is generally given as "and afterwards......" or something similar.

Legal Marriage

Legal marriage is where the government gets involved. The Marriage Act specifies and controls who can legally marry and what must be done in order that a marriage is recognised as legal. While a marriage is a contract between two people, it is the fact that, in front of witnesses and a duly authorised celebrant, marriage officer, or member of clergy, the couple makes the contractual statement that creates their marriage, and the marriage is subsequently registered  with the relevant government entity and recognised by government, that makes it legal. Legal marriage grants couples rights and benefts. And while most couples in Australia marry in a civil ceremony (70+%) a religious marriage ceremony is the only religious ceremony that delivers secular benefits.

Civil Union / Registered Partnership / Civil Partnership

Civil Unions are a mechanism by which a government  grants certain relationship entitlements to couples. In Australia while Marriage comes under Federal jurisdiction, Civil Unions, Registered Partnerships or Civil Partnerships are controlled by individual states. In Queensland couples can register their relationship with Births, Deaths, and Marriages as a Civil Partnership. This can be done purely as paper transaction or through a Declaration of Civil Partnership Ceremony.