Hi all. This is my first time in this interesting forum.
My name is aldo and I'm a composer and sound designer for videogames...
As a composer I write and produce the background music, the theme (when it's necessary) and songs for all the situations where developers want music.
as a sound designer I do make all the sfx of the game and when they are important the "enviromental sounds": I think the enviromental sounds are an hard job for a sound designer, but when the work is good the result is impressive.
about the softwares (the technical side of the story) sometime a composer and sound designer use the same softwares....especially sequencer and audio editing softwares.