Coilovers & Lowering Springs

My understandings about coilovers are a little bit blurry. The whole suspension thing gets me kinda confused. What is the difference between lowering springs and coilovers? Is coilovers your shocks and lowering springs combined???

Lowering springs are springs that are lower and tighter than stock. Coilovers are REALLY tight small springs that have a height adjustable perch with them. You can adjust the height by screwing the collars on the perch up or down. Trure coilover systems are both the hieght adjustabe shock with a coilover that was designed for use with that shock. There's a big difference between true coilovers and APC coilover sleeves.