Motion ratio is the ratio between the up and down wheel movement and the movement of the suspension. Linear and progressive are terms to describe the force loadings. For example let's say a linear spring is rated at 10kg/mm, so with 10kg loading the spring will move 1mm, 20kg will move the spring 2mm, 30kg will move the spring 3mm so on and so forth, if your spring length is 200mm, the effective spring rate at full compression is 2,000kg/mm. Progressive motion ratio can be increasing and decreasing. For all intents and purposes you can do some funky tuning with progressive rates, but ultimately linear rate is faster, at least in my experience.
