What is the difference between true bid'ah (religious innovation) and additional bid'ah?

Question:
He says: Honorable Shaykh, may Allah grant you success, what is the difference between true bid'ah (religious innovation) and additional bid'ah?

Answer:
True bid'ah (religious innovation) is that which has no basis in the religion. As for the additional one, it has a basis, but something is added to it or subtracted from the original, so this is additional. For example, fasting; voluntary fasting is a sunnah (recommended practice), but specifying it for a particular day or week without evidence is an additional bid'ah (religious innovation). You have added to what is prescribed something from yourself, specifying it for a time or place without evidence; this is the additional one.
Yes. The dhikr (remembrance of Allah), the remembrance of Allah (Exalted and Majestic is He), is prescribed (mashru'). Specifying it for a time or a number requires evidence. If you specify it for a time or a number without evidence, then this is an additional bid'ah (religious innovation). Yes.