The difference between Advantageous and Available

When used as adjectives, advantageous means being of advantage, beneficial, whereas available means such as one may avail oneself of.

check bellow for the other definitions of Advantageous and Available

Available as an adjective:

Such as one may avail oneself of; capable of being used for the accomplishment of a purpose.

Examples:

"We have an available candidate."
Available as an adjective:

Readily obtainable.

Examples:

"The list shows the available products in the store."
Available as an adjective (legal):

Valid.

Examples:

"This is an available plea."
Available as an adjective (archaic):

Having sufficient power, force, or efficacy to achieve the purpose; availing, effective.
Available as an adjective:

Free to meet someone, speak on the telephone, enter a romantic relationship or the like.

Examples:

"I have a question for you when you're available."

"Hi, this is Mark Smith calling. Is your mother available?"

"I asked her if she was available, but she said she had a boyfriend."