Its a misunderdstanding in regards to what a scientific theory actually is and also the distincion between theory and fact.
Evolution is both a fact or pretty damn close to it and a thoery at the same time. The thoery being an explanation based on the facts.
Scientests are in agreement that evolution happens. But the explanations for why it happens goes under the title of theory of evolution.
There is a distiction between the fact of the matter and the theory that attempts to explain the facts in science.
So the notion that Evolution is just a thoery isn't neccesarily valid if you're saying that creatures don't evolve, because that part of the science really isn't in question anymore. Of course one can call the theory of evolution a theory, because well it is.
But there is still a distinction between what a scientific theory is and what a theistic thoery is. Ones an attempt to explain and understand the facts of the natural world and one is an thoery that has no facts supporting it and deals in generally with realms that exist beyond the physical world. Hence why religion always has an emphasis on faith. Which is something science can't allow to be part of its method.
So no, you don't share the same thoeries, but neither do the theories share anything logically in common. Creationism has components that are near magical (or however you want to spin it) that have absolutely nothing to do with the perceptable world and thus can never be proven to have any varying degree of truth or correctness and thus isn't Scientific at all.
Not to mention that basings ones understanding of the natural world on a holybook that never changes (we'll disregard the constant manipulation of the bible over the years...) again isn't Scientific. Science is all about constant improvement of ones ideas about the universe. It changes. If a theory came out tomorrow that blew the thoery of evolution out of the water Science would eventually simply use that thoery instead once its been proven through peer review etc to be a better theory.