In the framework of causal perturbation theory by Epstein and Glaser the pr
ocess of renormalization is precisely equivalent to the extension of time-o
rdered distributions to coincident points. This is achieved by a modified T
aylor subtraction on the corresponding test functions. I show that the pull
back of this operation to the distributions yields expressions known from d
ifferential renormalization. The subtraction is equivalent to BPHZ subtract
ion in momentum space. Some examples from Euclidean scalar field theory in
flat and curved spacetime will be presented.