The comparison is valid but there doesn't even need to be a comparison.
The same CA Supreme Court first decided that not allowing gays to get married violated the Equal Protection Clause
A slim majority of voters later decided to take away that right and in essence over-ride the Equal Protection clause and the same CA Supreme Court decided it as valid to take away a previously recognized
right.
The whole thing is a mess
The voters didn't over-ride the Equal Protection Clause. What they did was re-establish marriage's original definition. The Court made its ruling, based on how the CA constitution read at that time last year.
The only reason this thing is a "mess" is because the CA court foolishly decided to allow gay "marriages" to take place, before the outcome of Prop. 8 arrived from the ballot box. That, and the actions of AG Brown, convinced me that the intent was to skew public opinion to vote Prop. 8 down.
That way, the judges look rosy, no matter what. They backed so-called marriage equality, yet the people had their say at the ballot box.
I believe this never should have gone to the court, in the first place. If there were any problems with Prop. 8, they should have been addressed LAST YEAR, before AG Brown and the court APPROVED it for ballot submission. You don't judge the amendment, based on the outcome of the election itself.
In short, if Prop. 8 wasn't "unconstitutional" last May, it shouldn't be "unconstitutional" this May.