Absolute references in excel are not updated when copied - and the relative are updated.
Just from this statement we can know that the following two statements are correct:
relative cell references in a formula are automatically updated if the formula is copied to other cells.
absolute cell references in a formula cause the reference to be locked
The phrase "the reference is not updated when the formula is copied"
- this is false, as at least in some way the expressin is updated.
When we look at the expression
= Sum(A$1:$B4)+25?, we see that row 1 and column B are locked
and
column A
row 4
are updated.
As far as value 25 is concerned - absolute values are never updated.