What is the difference between VAT and corporate tax Many times I hear that VAT (value added tax) is a "good" tax, while corporate tax is a "bad" tax/ However, both taxes take a cut from the difference between the income of a company and its expenses, and seem therefore to be economically equivalent. Can anybody explain the difference to me?
Both taxes take a cut from the difference between the income of a
  company and its expenses.


Wrong. Companies collect VAT as though they were tax-collectors on behalf of the state. This is why the amount of VAT that a company pays to its suppliers' is subtracted from the VAT that the company has collected from its customers, and only the difference is paid to the State. 

As to whether they are "good" or "bad" taxes, and which is which, as usual it is a complicated matter (and when you read/hear such assertions, make your eyes or ears walk away), a matter that has to do not only with businesses but with the macroeconomy as a whole, while it also depends on the current state of the business cycle, whether there is a depression, etc.

ADDENDUM
Responding to the comment by the OP to this answer, here is a schematic view of the matter


V.A.T is not part of the Revenues/Sales of a company. It is a tax imposed on consumers, and collected by the company on behalf of the state.  

Imagine a situation without V.A.T., i.e. assume that currently only the first column of the above exists. Then V.A.T. is enacted into tax law. The Profit and Loss statement of the company will not include it, neither in the Revenues side, nor on the Expenses side, it remains unchanged. The amount collected from customers goes up, but the Revenues of a company don't. And if among the company's customers are other companies, they will not see VAT as an increase in cost, because they will get to offset what they pay with what they collect from their customers. In other words, V.A.T is a tax imposed on final private consumers, and everybody else is involved as a tax-collecting entity only. Note that V.A.T is charged and collected irrespective of whether a company has profits or losses.

In a very general sense, all taxes are "equivalent" in the sense that they have the same goal: bring part of output under the ownership and control of the state. But it matters greatly how do they affect the "before-the-State" economy. In this particular case, V.A.T makes products more expensive for final consumers, and it is about how they will react to these increased prices. On the other hand, Income tax cuts directly from a company's profits, if profits exist, and so it affects the incentives of businesses to go into business.