It's one of those cases where perhaps at least a footnote to this effect as to that possibility is called for. As 'Marie Van Houtte' was, and is, a very well-known rose, with its (very vigorous) growth habit presumably also well known, it would be somewhat fatuous (at best) for a nursery to list the bush version as 'Climbing Marie Van Houtte', making it look as if it were somehow different from the bush; in such a case, the responsible thing would be to list it without the "Climbing" in the title, then with a sentence added, "Can also be used as a climber." But sometimes people are fatuous, sometimes people are irresponsible--and so the abovementioned "footnote to this effect" is called for. But in the absence of manifestly conflicting evidence in cases like this, my own philosophy is "take the listing at face value--and adjust if and when clearly compelling evidence shows up."