How does ponyboy explain that a gang and a pack are different?

"When you're a gang, you stick up for the members. If you don't stick up for them, stick together, make like brothers, it isn't a gang anymore. It a pack" Quoted from the book on page 26

He said:

Greaser:

. Poor

. Have leather jackets

. Broke down cars

Socs:

. Rich

. Nice cars

. Stripe shirts

Pony said they were different because a gang its free for all and a pack they look after each other and love each other like a family.