Every sports card collector will have their own category of baseball cards. It is common for them to categorize the cards according to their preference. Most of the sets that are common for categories of baseball cards have come from a vintage card and the popularity the card carried into this age. As there is a different category according to every collector, it is significantly difficult to keep track of the baseball cards and which category they fit in.

Rookie card
For such a common term of the set, the rookie cards are generally hard to define. Rookie cards, in simple words, are the first base cards of the players that later went on to be legends of the game. A Mickey Mantle rookie card will be more precious than the achievement baseball card of the player. These cards are the Holy Grail of card collecting due to their unique mystique and the investment potential they carry with them. According to the definition, the parallels, inserts, and sub-set cards do not qualify as rookie cards as they come under “rookie year cards”.

Sub-set card
Sub-set cards are theme-based cards of the players as well as teams. They include types of cards like all-star cards, league leaders, and World Series or playoff cards. For a card to qualify as a sub-set card, it must be included and must be numbered as the base set. These cards are different from the base as they have a different theme or design element from the conventional base cards.

Inserts
Insert cards are similar to sub-set cards in terms of theme and design, but they are not a part of a base card set. They are sold separately. Even the numbering on these cards is different from the main set of baseball cards. In some cases, the base cards do not even follow a numbering pattern. They are scarcer as compared to the base cards and are produced on the basis of ratios, for example, 1 in every 6 packs.