[Let me first say, as far as taxonomy goes I consider card games to be a sub-genre of board games, where the category 'board games' exists to differentiate it from other forms of tabletop games, namely tabletop RPGs. However, within the broad category of board games we find games that are mostly a single board and tokens and other games that are mostly cards. The purpose of this post is to look at the design spaces created by the different choice of components. I won't be looking at modular boards or tile games; those components fall somewhere in the middle of the spectrum.]
The primary purpose of components is to convey information. Different components are capable of better conveying different types of information. Public information may be either shared or personal, depending on how the information is intended to be used. Shared information is typically best presented by a board. A single board is easy to set up and is usually equidistant from all players. Information contained on a board is also typically constant information, information that does not change from game to game. Cards are more likely to be used to convey personal or private information- information that is only known to one player. Cards are also used for hidden information, information that is not known to any player. Because cards are easy to randomize by shuffling, they are well-suited for use in conveying variable information, information that changes throughout the game and/or from game to game.
Pawns on a grid are capable of conveying much finer spatial information than cards in the same amount of space. Most games with a strong spatial component have a central board that all players use. Pawns also make use of a third dimension, visually separating the information conveyed by the pawns from the information conveyed by the board. Both boards and cards make use of spatial information as a way to direct a player's gaze to what area is important or more important than another area. As discussed in the post on scale, size can be used to indicate what information is more important than other information. Size can also be used to indicate how a component is intended to be handled, such as poker-sized cards versus jumbo cards. Players will assume the cards best sized for human hands are the ones that should be held. Location of information can indicate what order the information should be processed, although this changes from culture to culture depending on the directionality of a language's writing system among other factors. Most people process visual information in roughly the same order they would read a page. Orientation can be used alongside location to further refine the relationship between components. Cards that are laid orthogonally to each other often trigger differently depending on orientation.
Another aspect of spatial information is how information (especially public information) is presented to players. Perspective is important for designers more so than players, especially when designing boards. Players play sitting down in a single location in the vast majority of tabletop games. A well-designed board should convey information to every player of average eyesight without a player needing to move around the table to get a better look. Cards are much easier to inspect and replace without upsetting the current play-state. Thus for cards, perspective is less of an issue. Distance is similar, but where perspective is about angle of view, distance is describes proximity to components. Scott Roger's zones of play should be considered here, as areas of play further from a player are generally more difficult for players to remember and interact with. As with perspective, components should not be so distant from players that they need to move around the table to see the information. And as always, how far a player has to reach for components will affect the rhythm of the game. Reach is a type of distance that focuses on how components are handled, not merely if they are legible. Any component meant to be shared should be easy for players to reach. This may require designing a space on the board for a card deck to live, for example.
Graphical information refers to all language, icons, and art (or illustration) printed on the game components. Language conveys both direct and indirect information. Large amounts of writing convey a different type of game experience than no writing. Lots of numbers and tables convey yet another type of game experience. Make sure that your game components are advertising the experience you intend. Writing on boards runs into the perspective problem detailed above. Cards are better suited for more and smaller text, although the size of the cards limits how much text can be included.
Icons and graphics have the advantage over language in that they are easier to 'read' upside down and don't need to be translated when marketing the game to a different language group. The downside is that too many icons can become a language in themselves, one that has no native speakers. Ideally, icons should be used to speed up and smooth out information processing, not create a new barrier to entry. One common way to do this is to use the graphical design of a board to clearly show where other components should live on the board, reducing the amount of information players have to remember when learning the game. I'm not an expert on UI/UX, but I found this page to be a useful overview of concepts.
Art can be used to set the mood, provide lore information, or merely organize mechanics in a more visually appealing way such as through a map of the area that players are attempting to control. Boards are better suited for landscapes, maps, and other large pieces of art that help establish the setting of the game. Cards are more appropriate for showcasing individual items or characters. In the case of cards, art allows players to identify a card faster than if the card was merely text. This is especially useful in set collection games, but the art must be distinct. I very much doubt even the most devoted fan would be able to match the spaceship illustrations to the cards in Space Base.
Finally, component choices convey genre conventions whether we intend them to or not. By choosing to design around a single shared board or a deck of cards, we set player's expectations as to the weight and style of the game. Card games have the expectation of being lighter and shorter, generally. Similarity to other games with regards to art and components also sets expectations. A beige game board with lots of rectangular spaces used as some sort of action selection mechanic will convey "dry euro game with little thematic integration that takes three hours to play." Subverting expectations can be a good thing, but that is difficult to do with visual information, because components are static and don't change to match tonal shifts in gameplay. And you still have to know the rules before you can break them.
To recap, types of information conveyed by components:
- General
- constant
- variable
- Use
- public (shared or personal)
- private
- hidden
- Spatial
- size
- location
- orientation
- perspective
- distance and reach
- Graphical
- language
- icons/graphics
- art/illustration
- Genre conventions/player expectations
That's a lot of information before even touching on specific rules or mechanics. Bottom line, the components you include in your game have a lot to say about what type of game it is, how you play, how accessible the game is, and how easy the game is to learn. A well-designed game's components convey all the necessary information about the game in a way that facilitates play. Well-designed components should not send mixed messages about their use.