I love splitting hairs.
There are two ways to address this:
1) Engineering as a department (designers)
2) Engineering as a function. (designing)
In the first, an "engineering change" is any change made by the engineering department. Even if it is just correcting spelling.
In the second, "engineering change" would apply only to an actual change in the product.
My understanding of the standards is that "Engineering" generally applies to the area, not the function.
Therefore in the case of Changing Rev A to Rev B, The "Engineering" dept made a change to the Design Record. Regardless of whether or not the part itself changed.
Therefore the customer must be notified so that their records can be updated.
Hope this helps
James