Broadheads
Broadheads are just that: they are a broad triangle of razor-sharp cutting edges. Often, the delta-shaped head is usually comprised of three or more blades. Broadheads are the arrowhead of choice for big game hunters. In fact, broadheads are the only legal big game hunting tip.
Types of Broadheads
Broadhead designs are really a class of arrowhead with many iterations on the theme. Roughly, though, they can be broken into a few sub-categories. A standard broadhead has fixed and permanent blades. These designs generally lead with the razor-edge, not bullet-like point, followed by flared cutting edges. Another subcategory is the removable blade, broadhead. These may look similar to a traditional bullet tip, with the addition of cutting blades that look similar to stabilizers on a rocket. The final category is an expandable blade. This is the most complex. It is a bullet-type tip. When it hits its target, flanges open cutting blades the way wind turns an umbrella inside out. The advantage is less flight drag of "open" blades, however, these require stronger bows as they need more impact-energy to operate.
Bullet
A bullet design is a classic, conical shape. The cone usually has a convex taper. These are also common range designs and work well with hair-bail targets. They have an advantage over target-only blunt heads as they are aerodynamic, giving you accurate range performance in the same tip you can use for small game hunting such as rabbit.
Field
A field tip is has a double taper, similar to the spire on top of the Chrysler building: it tapers, protrudes, then tapers again. This is essentially an iteration of the bullet design. However, the smaller primary taper gives it better penetration power making it a good choice for a less powerful bow.