What is the difference between curable and treatable?

Near enough every ailment, but there are some that humanity cannot yet cure, to name a few:

• Ebola
• Human Immunodeficiency Virus (H.I.V)
• Acquired immune deficiency syndrome (AIDS)
• Cancer
• Malignant tumours (Attached to an organ, making it impossible to remove without caffecting that organ)

Also, there are several (OK, quite a lot) of jungle diseases that haven't ever been heard of but are claiming the life of intrepid Explorers and Tribals alike.

Some manifestations of blindness can be cured as well.