There are four Type tools in Photoshop; they can be found under the Type tool fly-out menu in the Toolbar: the Horizontal Type tool, the Vertical Type tool, the Horizontal Type Mask tool, and the Vertical Type Mask tool (see Figure 13.4). The Type tools create vector-based text on type layers, while the Type Mask tools create "marching ants" selections in the shape of the characters that you type in, which you can then use as masks.
Truth be told, I've never really used the Type Mask tools, as you can achieve a similar result — that is, create a marching ants selection in the shape of your text — by creating a regular text layer and Ctrl+clicking/+clicking the layer thumbnail to create a selection from the text layer. The advantage to using this method is that if you need to, you can go back and edit the type layer, for instance, changing the font or the point size of the text, and re-creating the mask as necessary. On the other hand, Type Masks are gone forever once you've created the text.
The Horizontal Text tools create text that flows from left to right and from top to bottom, while the Vertical Text tools create type that flows vertically from top to bottom, and then across the page from right to left, as it does in Japanese books.