Inseam and lining are the two decisions that matter. Everything else is preference.
The Velocity 5" is the running short — short inseam, split hem for stride clearance, integrated liner so nothing shifts. The Pursuit 7" is lined and built for mixed training. The Foundation 7" is unlined, so you can layer as you prefer, with enough stretch to squat in without the leg riding. The Silk-Touch Lounge Short is the recovery option, cut relaxed and made for rest days and travel.
All four use four-way stretch fabrics with quick-dry finishes, and all four list inseam, lining and full fabric composition on their product pages.
