They both can resize. The control points are handled different. With Interactive curves the control points are within the curve / spline tool, where with the fixed curves the control points come from other tool points. By nature the fixed curve control points are porbably already adjusting to the tool’s formula, where with inter active cuvres you have to add formulas to the control pints to get smooth curves that resize properly. The topic has been discussed ad nauseam on the forums so I’m not going to rehash the topic.
You can try this topic…