Is 2.8 GHz bigger than 1.0 GHz?

No, a 2.80 GHz processor can run calculations significantly more quickly than a 1.8 GHz processor. Therefor, a computer with a 2.8 GHz CPU will tend to run more quickly than one with a 1.8 GHz CPU, depending on other limiting factors. If you can see no difference, then something else is slowing it down, like a lack of R.A.M.