What is the difference between a Capital Tax and a Capital Gains Tax?

Governor Romney has argued that Capital Gains should not be taxed because corporations are already taxed on their CAPITAL thus taxing capital gains effectively taxes that money twice. Now, in Canada, I've read that a corporation's working capital and assets are actually taxed, I guess that's kind of like a property tax -but I couldn't find a table of corporate capital tax rates for the US. In addition, I'm confused by the statement about the capital gains being "double taxed" since I would have supposed that say, a dividend paid out against a stock or similar asset wouldn't be part of the paying corporation's taxable assets, but that it is, in effect, income, for whatever individual or corporation receives such a capital gains payment. Obviously, I don't get it. Can anyone help?