For all intents and purposes there is no legal difference between a California Domestic Partnership and a California Marriage.*
However, there many social and psychological differences between the two.
Here are just a few:
Proposing
You DON'T propose Domestic Partnership.
You DO propose Marriage.
Easter morning I woke up early and quietly crept to Shannon's easter basket. I placed a box that contained a engagement ring in it.
When Shannon woke up I said hurry up let's go checkout what the Easter bunny brought us.
Shannon humored me by running down the hall to our baskets. (She thought I was excited because I'm Jewish and I love candy)
Shannon grabbed the box and said, "what's in here?"
I got down one knee and asked her to marry me.
Wedding Showers and Bachelor Parties
You DON'T have a wedding shower or a Bachelor Party when you are getting Domestic Partnered.
You DO have a wedding shower and/or a Bachelor Party when you are getting Married.
Our friends took us out for a bachelor/ette party.
We started out at a Karaoke bar and eventually ended up at House of Pies.
The Ceremony
You DON'T have a ceremony for a Domestic Partnership.
You DO have a ceremony for a Marriage

Shannon and I got married on June 30, 2008 in a courthouse in Contra Costa County.
I was so nervous that I said I do too early so I had to say I do twice.
When we turned to see our family we saw both of our moms crying tears of joy.
Tradition
You DON'T feed your spouse cake after you have been Domestic Partnered.
You DO feed your spouse cake after you have been Married.

As we drove back to LA many people honked at us. And some even gave us the thumbs up as they drove by.
With every honk and every thumbs up I felt so proud to have been "Just Married!"
Federal Differences
Along with the differences I mentioned above there are thousands of differences at the federal level. Please click here to read more about the differences between Domestic Partnerships and Marriages federally.
We started out at a Karaoke bar and eventually ended up at House of Pies.
The Ceremony
You DON'T have a ceremony for a Domestic Partnership.
You DO have a ceremony for a Marriage
Shannon and I got married on June 30, 2008 in a courthouse in Contra Costa County.
I was so nervous that I said I do too early so I had to say I do twice.
When we turned to see our family we saw both of our moms crying tears of joy.
Tradition
You DON'T feed your spouse cake after you have been Domestic Partnered.
You DO feed your spouse cake after you have been Married.
We fed each other spoonfuls of tiramisu cake.
You DON'T have "Just Domestic Partnered" written on your car.
You DO have "Just Married" written on your car.

You DON'T have "Just Domestic Partnered" written on your car.
You DO have "Just Married" written on your car.
With every honk and every thumbs up I felt so proud to have been "Just Married!"
Federal Differences
Along with the differences I mentioned above there are thousands of differences at the federal level. Please click here to read more about the differences between Domestic Partnerships and Marriages federally.