your talking about 300D arnt you,
adobe RGB paler, and less bright and contrasty with colour, but its better
for post procecing, parameter1 is if you arent going to do much prosesing.
Adobe 1998 is more vibrant once you open the image in Photoshop or any other profile-aware application. The gamut of colors recorded is much wider, and things like skin tones are rendered much better. I shoot just about everything in Adobe 1998, and then convert to sRGB later in Photoshop.