They are generally used interchangeably in common english. It is similar to the difference between due to and because of. Though you can switch them you would ascribe something to a noun. Example: I would ascribe the symptoms to allergies. Attribute is similar to because of. You use because of a verb. Example: I would attribute the symptoms to running in the cold. Attribute can also mean a characteristic if you are using the word differently! Also, in comparison to ascribe... attribute is more commonly used in english when discussing the causes of things.

"Ascribe" is like you put a type of upgrade in something, in the case, this "upgrade" is an "attribute". Correct me if i wrong