block: A portion of text that is selected in a document; this can range from a single character to the entire document. By marking off text as a block, you can perform certain actions, or use various Word commands, that affect only the text in that block. You can also copy or move the block of text.

border: A line that is added above, below, or to either side of a paragraph. A border is useful for setting a block of text apart from surrounding text.