<p><strong>Conjunction:</strong></p><ul><li>Used after comparative adjectives and adverbs to introduce the second member of an unequal comparison.<ul><li>Example: She's taller than I am.</li></ul></li><li>Used after some adverbs and adjectives expressing choice or diversity, such as other, otherwise, else, anywhere, or different, to introduce an alternative or denote a difference in kind, place, style, identity, etc.<ul><li>Example: I had no choice other than that.</li><li>Example: You won't find such freedom anywhere else than in this country.</li></ul></li><li>Used to introduce the rejected choice in expressions of preference.<ul><li>Example: I'd rather walk than drive there.</li><li>Example: We had no choice than to return home.</li><li>Example: We had barely arrived than we had to leave again.</li></ul></li></ul><p><strong>Preposition:</strong></p><ul><li>In relation to; by comparison with (usually followed by a pronoun in the objective case).<ul><li>Example: He is a person than whom I can imagine no one more courteous.</li></ul></li></ul>