The difference between the two –demics, according to Merriam-Webster Dictionary, is that an epidemic is “an outbreak of disease that spreads quickly and affects many individuals at the same time.” On the other hand, a pandemic is a type of epidemic (one with greater range and coverage), an outbreak of a disease that occurs over a wide geographic area and affects an exceptionally high proportion of the population.

Epidemic = may be traced to the Greek epidḗmios (“within the country, among the people, prevalent (of a disease)”), may carry broader meanings, such as “excessively prevalent,” “contagious,” or “characterized by very widespread growth or extent” (often used in a non-medical sense):

Mother remembered hearing about the plague epidemic which had struck the town when she was 10.

The ship’s captain came down with the influenza and an onboard epidemic occurred.

An epidemic of SARS affected 26 countries and resulted in more than 8000 cases in 2003.

Haiti’s 2010 cholera epidemic went on for nearly a decade and killed nearly 10,000 people.

Sleepy Joe Biden was in charge of the H1N1 Swine Flu epidemic which killed thousands of people: Donald J. Trump 

Some more examples

After epidemics such as plague, cholera, smallpox and syphilis infected their first patients, they spread widely via means of transport.

A cholera outbreak/epidemic can occur in both endemic countries and in countries where cholera does not regularly occur.

Foot and Mouth disease is one which affects livestock such as cows and sheep, and is incredibly infectious.

An outbreak of severe acute respiratory syndrome, better known by its acronym, SARS, tore through the city in 2003, leaving 299 people dead.

Before the novel coronavirus, many momentous epidemics and pandemics altered the course of human history, killing large percentages of the global population.

Pandemic = is less often encountered in a broad and non-medical sense, but does have additional senses, including “affecting the majority of people in a country or a number of countries”, “found in most parts of the world and in varied ecological conditions,” and “of or relating to common or sensual love” (in this last sense the word is usually capitalized). Pandemic comes from the Greek pandēmos (“of all the people”), which itself is from pan- (“all, every”) and dēmos (“people”):

Unlike an epidemic, a pandemic affects people worldwide.

The main thing about a pandemic like the novel coronavirus is that it doesn’t discriminate.

The most deadly pandemic in history was the Spanish flu of 1918.

The World Health Organization has declared the novel coronavirus outbreak a pandemic.

The epidemic had rapidly become a pandemic, making its way around the world.

COVID-19 began as an epidemic in China, before making its way around the world in a matter of months and becoming a pandemic.

Epidemics don’t always become pandemics, and it’s not always a fast or clear transition.

Some more examples

The COVID-19 pandemic is distinct from previous global outbreaks.

The last pandemic declared was in 2009 during the outbreak of H1N1 flu, commonly known as the swine flu.

The first cholera pandemic occurred in 1817 and originated in Russia, where 1 million people died.

In 1918, the Spanish flu caused a global pandemic, spreading rapidly and killing at least 50 million people, making it the deadliest pandemic in modern history.

Should schools be closed for a few weeks, as a way of short-circuiting the pandemic?

Europe has now become the epicenter of the pandemic, with more reported cases and deaths than the rest of the world combined, apart from China.

President just declared the coronavirus pandemic a national emergency.  

Even if countries vaccinate their citizens, they will not remain immune to the pandemic shock.