Givre beads and Porphyr beads are very similar.
Givre beads are clear beads with a cloud of color in the center or in part of the bead. Some suppliers will list beads that have a small bit of clear glass in them as givre beads, but this is not accurate.
Porphyr beads have two or more colors in a stripe or swirl pattern; one of the colors is usually white and swirled with the other color. Some suppliers will list beads that are clear, white, and colored as porphyr.