I will just say, that today I walked by a large number Saguaros that looked exactly like that in a big box store. Not to say it makes me certain it is a Saguaro, but just to say that at that size these plants do not yet have a highly distinguished shape or form. It could be either, if it has been out in serious frost, it is probably a Saguaro as a Cardon would likely be toast. If not then it is just a matter of time and growth... in a few years things will differentiate enough to be able to tell. Regardless, given enough time it will grow into a monster.
So I agree wholeheartedly with Nancy, even if it is not your house but just a wall, you should move it, the wall (and certainly your house) will not like what this plant will become if it survives and grows.