LLC switching bridge gain

Hello,
can someone kick me a little bit? Why is switching brifge gain 0.5 for halfbridge and 1 for fullbridge?
Both are connected with (resonant tank + transformer) trough transistor to VIN.
thanks

With a full bridge, Vsw laternates between +supply and -supply; it always has the supply voltage, in one polarity or the other.

With a half bridge, it alternates between + supply and 0V. After Cr, that will give + or - half supply.

Compare it to "bridging" two normal audio amps to give higher power to the speaker. That's like going from a half bridge to a full bridge, doubling the possible voltage swing at the load.