The Drift is designed for relatively straight lines that need a gentle fade at the end. It will glide for days (not actually proven, so take it for melody), providing easy distance for even average throwers. It has a modest rim size, a slightly domed profile, and an easily activated turn for hyzer-flips or big turnover shots.
Streamline is a new company from MVP Disc Sports. And while MVP has perfected overmolding, they wanted the chance to come up with a more classical line of "solo-mold" discs. Thus, Streamline was born.
They've also managed to - ahem - streamline their production process for their new molds to ensure a consistent line of discs that avoid the hassles sometimes confronted with other lines of discs.