A marriage license is often confused with a marriage certificate (marriage contract). Many are of the mistaken view that they are synonymous. But they are not.
A marriage license is the written permission issued by the civil registrar to the contracting parties authorizing their marriage before any authorized solemnizing officer. In brief, it is the authority to marry.
On the other hand, a marriage certificate is a documentary evidence to prove the existence of the marriage. It is, in fact, the best evidence to prove the same.
Nevertheless, in the absence of the marriage certificate, the existence of the marriage may be proven by some other forms of evidence, namely: the testimonies of witnesses, land titles, declaration of one of the contracting parties, last will and testament, and by the legal presumption that a man and a woman deporting themselves as husband and wife have entered into a lawful contract of marriage.
A marriage license is one of the formal requisites of marriage found in Article 3 of the Family Code of the Philippines. As such, its absence will, as a rule, render the marriage void.
In stark contrast, a marriage certificate is neither an essential nor a formal requisite of marriage. Consequently, its absence will not affect the validity of the marriage.
The form for the application for marriage license is filled out and signed by the contracting parties prior to the solemnization of their marriage and is sworn to before the local civil registrar, while the marriage certificate is executed and signed by the contracting parties, their witnesses, and the solemnizing officer at the place of marriage only afterwards.
[References: Page 6 of The Family Code of the Philippines Annotated [2001 Edition] by Dean Ernesto L. Pineda, Article 3 of the Family Code of the Philippines (Family Code), Article 4, in relation to Article 35 (3), of the Family Code, and Article 2 of the Family Code]