The difference between Common and Ordinary

When used as nouns, common means mutual good, shared by more than one, whereas ordinary means a devotional manual.

When used as adjectives, common means mutual, whereas ordinary means having regular jurisdiction.

Common is also verb with the meaning: to communicate (something).

check bellow for the other definitions of Common and Ordinary

Common as an adjective:

Mutual; shared by more than one.

Examples:

"The two competitors have the common aim of winning the championship."

"Winning the championship is an aim common to the two competitors."
Common as an adjective:

Occurring or happening regularly or frequently; usual.

Examples:

"It is common to find sharks off this coast."
Common as an adjective:

Found in large numbers or in a large quantity.

Examples:

"Sharks are common in these waters."
Common as an adjective:

Simple, ordinary or vulgar.
Common as an adjective (grammar):

In some languages, particularly Germanic languages, of the gender originating from the coalescence of the masculine and feminine categories of nouns.
Common as an adjective (grammar):

Of or pertaining to common nouns as opposed to proper nouns.
Common as an adjective:

Vernacular, referring to the name of a kind of plant or animal, i.e., common name vs. scientific name.
Common as an adjective (obsolete):

Profane; polluted.
Common as an adjective (obsolete):

Given to lewd habits; prostitute.

Common as a noun:

Mutual good, shared by more than one.
Common as a noun:

A tract of land in common ownership; common land.
Common as a noun:

The people; the community.
Common as a noun (legal):

The right of taking a profit in the land of another, in common either with the owner or with other persons; so called from the community of interest which arises between the claimant of the right and the owner of the soil, or between the claimants and other commoners entitled to the same right.

Common as a verb (obsolete):

To communicate (something).
Common as a verb (obsolete):

To converse, talk.
Common as a verb (obsolete):

To have sex.
Common as a verb (obsolete):

To participate.

Examples:

"rfquotek Sir Thomas More"
Common as a verb (obsolete):

To have a joint right with others in common ground.

Examples:

"rfquotek Johnson"
Common as a verb (obsolete):

To board together; to eat at a table in common.

Ordinary as an adjective (legal, of a judge):

Having regular jurisdiction; now only used in certain phrases.
Ordinary as an adjective:

Being part of the natural order of things; normal, customary, routine.

Examples:

"On an ordinary day I wake up at nine o'clock, work for six hours, and then go to the gym."
Ordinary as an adjective:

Having no special characteristics or function; everyday, common, mundane; often deprecatory.

Examples:

"I live a very ordinary life most of the time, but every year I spend a week in Antarctica."

"He looked so ordinary, I never thought he'd be capable of murder."
Ordinary as an adjective (Australia, New Zealand, colloquial, informal):

Bad or undesirable.

Ordinary as a noun (obsolete):

A devotional manual.
Ordinary as a noun (Christianity):

A rule, or book of rules, prescribing the order of service, especially of Mass.
Ordinary as a noun:

A person having immediate jurisdiction in a given case of ecclesiastical law, such as the bishop within a diocese.
Ordinary as a noun (obsolete):

A set portion of food, later as available for a fixed price at an inn or other eating establishment.
Ordinary as a noun (archaic, _, or, _, historical):

A place where such meals are served; a public tavern, inn.
Ordinary as a noun (heraldry):

One of the standard geometric designs placed across the center of a coat of arms, such as a pale or fess.
Ordinary as a noun:

An ordinary thing or person; the mass; the common run.
Ordinary as a noun (historical):

A penny-farthing bicycle.