These six types of power differ based on the dynamics between the parties involved.
Coercive power refers to a dynamic in which one party has the ability to punish the other. In the context of a marriage, this might look like one spouse constantly conceding to the other to "keep the peace."
Reward power refers to one party's ability to incentivize the other party with a reward. In a marriage, this might look like one party promising the other a gift to get them to agree to something they wouldn't ordinarily do.
Expert power is power held by virtue of expertise. If, for example, one spouse knows how to fix something that the other doesn't, the spouse with the needed knowledge holds the power.
Legitimate power is power held by virtue of one's role as an authority. This is much trickier in a marital context, since both parties are equal legal partners in the relationship. There are, however, rare circumstances in which this might not be true—if, for example, an injury leaves one spouse unconscious, the other might be designated "power of attorney" and have the legal authority to make decisions on behalf of the unconscious party.
Referent power refers to power held on the basis of one's personality. In a relationship, this might look like one party constantly "charming" the other into doing what they want.
Informational power refers to the power one holds when in possession of privileged information. Between spouses, who are often each others' confidants, this might manifest as one person threatening to share the other's secrets if they don't comply.