Here are some of the main differences and examples of how to use them correctly:

• Passed is the past tense and past participle of the verb pass, meaning to move on or ahead; proceed. It can function as both a transitive and intransitive verb. For example, "She passed the exam" or "He passed by the store". ^{9 1 11}
• Past can function as several different parts of speech, each with different meanings, though the most common usage of past is as a noun to indicate an earlier time or era. It can also function as an adjective, adverb, or preposition and mean the following things: ^{9 1 11}
• Noun: Past means "an earlier period of time". For example, "Houses were more affordable in the past".
• Adjective: Past can also be used to describe a noun. In this form, past also means "gone by in time". For example, "In past summers, we’d go to the beach in Delaware".
• Adverb: The word past is also a common adverb used to describe a verb or adjective and can indicate passing from one side of something to the other. For example, "Ari worked past his issues with Gina".
• Preposition: Lastly, past as a preposition is typically used to tell time or to refer to being beyond a particular point or stage. For example, "It is half past five o’clock" or "The milk was past its expiration date".