People use "leggings" and "yoga pants" interchangeably, but they are not exactly the same.
Leggings
Fitted, stretchy pants that hug from waist to ankle. Range from casual to high-performance.
Yoga Pants
Originally for yoga. Slightly thicker, wider waistband, sometimes flared.
Which to Buy?
Gym: GPS High Waist Leggings ($60). Yoga/everyday: GPS Compression Flared Pants ($60).
Shop at gpsfitwear.com.au.