I am skeptical too about similarities between maths and computer science.
I would say they both need a similar mindset, i.e. being comfortable
with dealing with strict logic, in that they both are exact sciences.
But their respective subjects are quite different, I think.
The math domain ranges e.g. from (numerical) space topology to
functional analysis, space transformations, calculus and so son.
Computer science ranges e.g. from resource management to modeling,
complexity management, networking/communications, and so on.
(obviously not exhaustive listings, but I think they give the idea)
In my line of work I deal with calculation software for the applied
domain we work in, but even in this context only a fraction of my code
is actual computation, most of it is about UI, modeling, I/O,
interfacing, data storage, etc.