def compare_one(a, b):
    """
    Create a function that takes integers, floats, or strings representing
    real numbers, and returns the larger variable in its given variable type.
    Return None if the values are equal.
    Note: If a real number is represented as a string, the floating point might be . or ,

    compare_one(1, 2.5) ➞ 2.5
    compare_one(1, "2,3") ➞ "2,3"
    compare_one("5,1", "6") ➞ "6"
    compare_one("1", 1) ➞ None
    """
    temp_a, temp_b = a, b
    if isinstance(temp_a, str): temp_a = temp_a.replace(',','.')
    if isinstance(temp_b, str): temp_b = temp_b.replace(',','.')
    if float(temp_a) == float(temp_b): return None
    return a if float(temp_a) > float(temp_b) else b