Both lines configure the first port to drive a soundblaster card in 1200 baud AFSK mode. The channel access parameters can be set with sethdlc -a or kissparms. Note that both utilities interpret the values slightly different. It is important that the input and output levels are adjusted properly. See the respective man pages.
Functionality is the same, though.
MPU401 MIDI output via a retriggerable monoflop. The sound driver and the soundcard modem driver compete for the same hardware resources. Of course only one driver can access a given interface at a time. Worse yet, the sound driver grabs the soundcard at startup time. Therefore the soundcard modem driver subsequently won't be able to access the soundcard.