A linear-rate spring is evenly wound from top to bottom so that the force (road surface bumps and potholes, acceleration and braking) remains the same from the initial input right through to when the spring won’t compress any further. They come in hard, and soft versions, but they retain the same force throughout their length!
A progressive or dual-rate spring is wound closer at one end and further apart at the other. So, the more the spring is compressed, the more it resists.
The Emulators? Better wait for FBOAB. He fitted them to std. B12 forks, and was impressed with them.