Wether clothing and accessories are considered Vintage or second hand is mostly a matter of how old the item is.
An item is considered Second Hand when it has been previously owned by at least one other person, no matter how old it is. The retail value and quality often determines the second hand value of items with designer handbags still costing hundreds of dollars in second hand stores.
For an item to be considered Vintage by the commonly accepted industry standard, it needs to be at least 20 years old, but does not have to have been previously owned by someone else. However, because of their age, many vintage pieces are second hand. Condition, material composition and brand all influence the second hand value of a vintage piece.
Once an item gets older than 100 years it is no more considered vintage but becomes an Antique.