The difference between Sad and Sorry

When used as adjectives, sad means feeling sorrow, whereas sorry means regretful for an action.

Sorry is also interjection with the meaning: expresses regret, remorse, or sorrow.

Sorry is also noun with the meaning: the act of saying sorry.

check bellow for the other definitions of Sad and Sorry

Sad as an adjective:

Emotionally negative. Feeling sorrow; sorrowful, mournful. Appearing sorrowful. Causing sorrow; lamentable. Poor in quality, bad; shameful, deplorable; later, regrettable, poor. Of colours: dark, deep; later, sombre, dull.

Examples:

"She gets sad when he's away."

"The puppy had a sad little face."

"It's a sad fact that most rapes go unreported."

"That's the saddest-looking pickup truck I've ever seen."
Sad as an adjective (obsolete):

Sated, having had one's fill; satisfied, weary.
Sad as an adjective (obsolete):

Steadfast, valiant.
Sad as an adjective (obsolete):

Dignified, serious, grave.
Sad as an adjective (obsolete):

Naughty; troublesome; wicked.
Sad as an adjective (slang):

Unfashionable; socially inadequate or undesirable.

Examples:

"I can't believe you use drugs; you're so sad!"
Sad as an adjective (dialect):

Soggy (to refer to pastries).
Sad as an adjective (obsolete):

Heavy; weighty; ponderous; close; hard.

Examples:

"sad bread"

Sorry as an adjective (of a person):

Regretful for an action; grieved or saddened, especially by the loss of something or someone.

Examples:

"I am sorry I stepped on your toes. It was an accident."

"I am sorry to hear of your uncle's death."
Sorry as an adjective:

Poor, sad or regrettable.

Examples:

"The storm left his garden in a sorry state."
Sorry as an adjective:

Pathetic and inferior to the point of causing others disgust.

Examples:

"Bob is a sorry excuse for a football player."