In English, we make comparative forms by adding –er and –est to the positive form.

Examples are given below:

Tall, taller, tallest
Short, shorter, shortest
Bright, brighter, brightest

In some cases, we use more and most before the adjective in the positive degree.

Careful, more careful, most careful
Intelligent, more intelligent, most intelligent

There are also a few comparative adjectives ending in –or. All of these words were borrowed from Latin. They are: interior, exterior, ulterior, major, minor, inferior, superior, junior, senior, anterior, posterior and prior.

Five of these words – interior, exterior, ulterior, major, minor – have lost their comparative meaning. They are now used as positive adjectives.

He had a major accident.
He sustained minor injuries.
She is an interior designer.
These awnings complement the exterior of your home.
I suspect he has some ulterior motives.

Note that we do not use than or to after these adjectives because they have lost their comparative meaning.

The remaining seven adjectives – inferior, superior, junior, senior, anterior, posterior and prior – have retained their comparative meaning. They are followed by to, not than.

My job is superior to yours. (NOT My job is superior than yours.)
Mary is senior to me by six years. (NOT Mary is senior than me.)
Peter is junior to me in service.