With examples from Stargate SG-1
Even though these words share a similar meaning, "pertaining to society," they are still different in the way they are used. Social, for instance, is an adjective that is usually used when referring to individuals, as well as their behaviors and needs when interacting with others. Social is also sometimes used as a noun when paired with an event, such as a social gathering or a church social, which is primarily used to promote companionship.
"You're a regular social butterfly," Jack said dryly. Daniel shrugged, but Jack couldn't let it go. "Why do you have to talk to everyone you meet?"
"Looks like some kind of social event," Daniel responded. "The least we can do is talk to our hosts."
Many people are drawn to the social events and clubs listed above so they can socialize, meaning to mingle with others.
Teal'c stood in front of a building constructed of bricks and a sign that glowed brightly in the darkness of the night. "It's a nightclub," Captain Carter told him. "It's a place where we go to socialize and meet new people."
This leads us to societal which is defined by Dictionary.com as noting or pertaining to large social groups, or to their activities, customs, etc.
"It is their way of life," Teal'c said. "These rites and traditions are merely a societal matter practiced by their ancestors."
Society can also be viewed as pertaining to large social groups, but it is a more structured system, such as "a body of humans living as members of a community."
"Many of the elders tend to look down on those who are deformed in some way," Daniel said. "They believed that these people were a detriment to the society as a whole."
As you can see there is a difference between the words, even if they do share the same root. Just remember that social and socialize pertains primarily to individuals and their behaviors within society, and society and societal pertain to groups of people, such as communities and organizations.
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