Cutters are small, felt-tipped markers, loaded with either ink or paint. They are convenient for doing small scale tags, as they are often small enough to fit in trouser pockets, but they are also used for details on larger, multicolored work. The tip is beveled, giving the user control over the size of the line they put down. You can find them in several colors, and occasionally empty, so you can add a custom color of paint.
Broad tip markers have a wide rectangular tip, which allows artists to paint broad, dark lines. The rectangular tips can be as wide as 2 1/4 inches. Broad tip markers don't take up as much space in your pocket or backpack as a spray can, but can deliver as wide and dark a line in ink. They are great for medium sized tags, though they can run out of ink if used for larger artwork. They cannot mark on all surfaces, either; the felt tip usually works best for metal or wood.
The mop tip marker delivers a wide, wet line in a circular shape. The tip is fibrous and can put out a lot of ink or paint. It suits situations when an artist needs to deliver an opaque line fast. The mop brush is also capable of writing on almost any surface, but the bristles can pick up dust or dirt and become blotchy or clogged. Because the mop tip puts out so much liquid, the resulting tag can drip, which may or may not be desired.
Metal tips refer to markers with a rounded metal tip with a ball in the center for paint delivery. The design is similar to a giant ball point pen. They can be used on any surface, even something as difficult to paint on as rust. They are not able to deliver as wide a line as their felt tipped counterparts, but the artist does have good control over the amount of paint leaving the bottle at any given time. These markers do tend to have wider ink reservoirs, making them difficult to carry in pants pockets.
Squeeze marker refers to a style of ink reservoir that is made from a soft, squeezable plastic. Squeeze markers can be equipped with almost any tip. They allow the artist to control the amount of paint flowing to the tip, giving them control over a combination of coverage and line size, depending on the tip. Squeeze markers come in all shapes and sizes, some small enough to fit in trouser pockets, and others large enough to hold paint for elaborate projects.