X multiplied by X would be X squared, which is what I think you meant by x^2 (it's an 'x' with a little 2 just to the right of it and near the top).
2x is 2 multiplied by X.
Is x times x x^2 or 2x?
x multiplied by x is x^2
x + x = 2x or x multiplied by 2 is also 2x, it's the same thing
eg. 1^2 = 1 while 1 + 1 = 2 (1 multiplied by 2 is 2)