Comparative is used to compare two things, while superlative is used to compare more than two things. To form the comparative, add -er to the end of the adjective or use 'more' + adjective. To form the superlative, add -est to the end of the adjective or use 'most' + adjective. Some adjectives have irregular forms for comparative and superlative. Adverbs use 'more' or 'most' to form comparative and superlative. Some adverbs have irregular forms for comparative and superlative.