The difference between Jovial and Merry

When used as adjectives, jovial means pertaining to jove or zeus, whereas merry means jolly and full of high spirits.

Merry is also noun with the meaning: an english wild cherry.

check bellow for the other definitions of Jovial and Merry

Jovial as an adjective (obsolete):

Pertaining to Jove or Zeus; Jovian.
Jovial as an adjective (obsolete):

Pertaining to the planet Jupiter; Jovian.
Jovial as an adjective (astrology, obsolete):

Under the influence of the planet Jupiter (considered a source of happiness).
Jovial as an adjective:

Merry; cheerful and good-humored.

Examples:

"ant saturnine"

Merry as an adjective:

Jolly and full of high spirits.

Examples:

"We had a very merry Christmas."
Merry as an adjective:

Festive and full of fun and laughter.

Examples:

"Everyone was merry at the party."
Merry as an adjective:

Brisk

Examples:

"The play moved along at a merry pace."
Merry as an adjective:

Causing laughter, mirth, gladness, or delight.

Examples:

"a merry jest"
Merry as an adjective (euphemistic):

drunk; tipsy

Examples:

"Some of us got a little merry at the office Christmas party."