Cousin-ness and removal is determined by common ancestry.
If you are the same number of generations from a common ancestor,
you are just a plain cousin, where the number is one less
than the number of generations.
Common GRANDparent (2 generations):FIRST cousins.
Common GREAT-grandparent (3 generations):
When the number of generations is NOT equal,
then the Removals come in.
The child of your Nth cousin
is your Nth cousin-once removed.
The grandchild of your Nth cousin
is your Nth cousin-twice removed.