McCulloch, whose Rangers are 20 points clear in the third division, said: "Having played in the SPL myself I don't think there's that much of a gap between the top flight and League One.
"I can't really draw a comparison between the two because I have never worked or played consistently at that level," he said. "But I would imagine the majority of the football people in the country would disagree with that point of view.
"Last season Queen of the South won that league by a canter but haven't made great inroads into the Championship this season so that would tell you that there is a gulf between League One and the Championship."
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