The SH775 is a series type. This type works by limiting the power out of the alternator by varying the resistance. Basically, this prevents your alternator from putting out full power unless it is needed.
The FH020AA is the shunt type were were talking about. With this setup, your alternator is always putting out full power, but the regulator bleeds whatever isn't needed back to ground.
Series type is generally considered to be superior, but is usually more expensive, too.