The difference between Before and Previously

When used as adverbs, before means at an earlier time, whereas previously means at an earlier time.

Before is also conjunction with the meaning: in advance of the time when.

Before is also preposition with the meaning: earlier than (in time).

check bellow for the other definitions of Before and Previously

Before as a preposition:

Earlier than (in time).

Examples:

"I want this done before Monday."
Before as a preposition:

In front of in space.

Examples:

"He stood before me."

"We sat before the fire to warm ourselves."
Before as a preposition:

In the presence of.

Examples:

"He performed before the troops in North Africa."

"He spoke before a joint session of Congress."
Before as a preposition:

Under consideration, judgment, authority of (someone).

Examples:

"The case laid before the panel aroused nothing but ridicule."
Before as a preposition:

In store for, in the future of (someone).
Before as a preposition:

In front of, according to a formal system of ordering items.

Examples:

"In alphabetical order, "cat" comes before "dog", "canine" before feline"."
Before as a preposition:

At a higher or greater position than, in a ranking.

Examples:

"An entrepreneur puts market share and profit before quality, an amateur intrinsic qualities before economical considerations."

Before as an adverb:

At an earlier time.

Examples:

"I've never done this before."
Before as an adverb:

In advance.
Before as an adverb:

At the front end.