The English we speak and write appears to be simple enough to be easily understandable by everyone. But when it comes to the grammar, the simplicity is somewhat lost. The grammar of any language is the most difficult yet most important component that an individual must comprehend fully in order to ace that language.
She ate a red apple.
She ate a bigger apple then her sister.
In the above example, the word bigger is the adjective that is used to describe the noun apple. Now in this example, the adjective not only describes the noun but also compares it with another noun i.e. the apple her sister ate, thus it is known as comparative adjective.
I am more comfortable in this seat.
Now consider the above example. This sentence also contains a comparative objective but that is not in the form of adding –er at the end of a word but adding more before it. The term more comfortableshows that the speaker is comparing two seats and find one more comfortable, hence comparative adjective is used.