1. Design and Appearance:
- K-Style Gutters: These gutters have a rectangular or square shape in cross-section, with a flat back and a front that resembles the letter "K" when viewed from the side. They are more angular and have a modern appearance.
- Half-Round Gutters: Half-round gutters have a shape like a tube cut in half longitudinally, resulting in a semi-circular cross-section. They have a smoother, rounded appearance.

2. Installation and Mounting:
- K-Style Gutters: They are often installed using hidden hangers that are attached to the fascia structure.
- Half-Round Gutters: These gutters are also installed using brackets but require a different mounting style due to their specific shape.

3. Water Flow:
- K-Style Gutters: Due to their angular design, K-style gutters can handle somewhat better large volumes of water, such as those from steeper roofs or areas with heavy rainfall.
- Half-Round Gutters: While still effective in draining water, half-round gutters may have slightly lower performance in terms of the maximum volume of water they can carry due to their smoother shape.

4. Architectural Style:
- K-Style Gutters: They are more common in modern or contemporary constructions, although they can also be found in more traditional styles.
- Half-Round Gutters: These gutters have a more classic appearance and are often associated with older architectural styles such as Victorian or rural houses.