What is the main difference between cortical and senile cataract.?

Cataract types: A cataract is a clouding of the natural lens of the eye. Most people will develop a diffuse clouding of the lens with age. This is referred to as a "nuclear sclerotic" cataract, or a senile cataract. It develops slowly after age 50-60, and may never have to be removed. A cortical cataract is a clouding usually on the front of the lens and may cause signficant glare. It may develop more quickly.

Cataract: Cortical cataract is a change in the peripheral portion of the crystalline lens which extends centrally. Senile cataract is a yellowing of the entire crystalline lens. Both cause decreased vision over time.

Where the opacity is: We generally divide cataracts by the location. Senile cataracts would include all types. Nuclear cats occur in the nucleus or center of the lens, cortical (often seen in diabetics) in the cortex, and capsular cataracts next to the capsule of the lens. All are senile cataracts, but I have heard senile cataracts used to describe nuclear cataracts. All when bad enough require surgery.

Cataract: Cortical cataract is clouding of the outer shell of the lens, "Cortical". Senile is clouding of the lens (does not specify what portion or layer).