They are similar. They differ in the ordering of rule application, but
there is also an issue of re-simplification. That is, you don't want
to get into a recursion because the argument to a rule is first
simplified. (calling the rule ... etc). The situation with tellsimpafter
requires a different trick. But otherwise I think the code generated
is the same. (At least that is what I recall from when I wrote this
stuff in 1969 or so...)
RJF