Main Difference
The main difference between Century and Decade is that the Century is a unit of time lasting 100 years and Decade is a period of 10 years.
Century
A century (from the Latin centum, meaning one hundred; abbreviated c.) is a period of 100 years. Centuries are numbered ordinally in English and many other languages.
A centenary is a hundredth anniversary, or a celebration of this, typically the remembrance of an event which took place a hundred years earlier.
Decade
A decade is a period of 10 years. The word is derived (via French and Latin) from the Ancient Greek: δεκάς, translit. dekas), which means a group of ten. Other words for spans of years also come from Latin: biennium (2 years), triennium (3 years), quadrennium (4 years), lustrum (5 years), century (100 years), millennium (1000 years).
Century (noun)
A period of 100 consecutive years; often specifically a numbered period with conventional start and end dates, e.g., the twentieth century, which stretches from (strictly) 1901 through 2000, or (informally) 1900 through 1999. The first century AD was from 1 to 100.
Century (noun)
A unit in ancient Roman army, originally of 100 army soldiers as part of a cohort, later of more varied sizes (but typically containing 60 to 70 or 80) soldiers or other men (guards, police, firemen), commanded by a centurion.
Century (noun)
A Centuriate Assembly.
Century (noun)
A hundred things of the same kind; a hundred.
Century (noun)
A hundred runs scored either by a single player in one innings, or by two players in a partnership.
Century (noun)
A race a hundred units (as meters, kilometres, miles) in length.
Century (noun)
A banknote in the denomination of one hundred dollars.
Decade (noun)
A series or group of ten entities. from 16th c.
“a decade of soldiers”
Decade (noun)
A historical period of the ten years in which the beginning year ended in “0” and the ending year ended in “9”.
“The 1960s was a turbulent decade.”
Decade (noun)
Any given period of ten years. from 17th c.
“I haven’t seen my cousin in over a decade!”
Decade (noun)
In the French Revolutionary calendar, a group of ten days. from 18th c.
Decade (noun)
A series of ten beads (or the prayers associated with them) in the rosary
Decade (noun)
The interval between any two quantities having the ratio 10 to 1.
“There are decades between 1.8 and 18, between 25 and 250 and between 0.03 and 0.003.”
Decade (noun)
Any of the sets of ten sequential braille characters with predictable patterns.