How are sills different from dikes?

Sills and dikes are both intrusive igneous rock formations, but they differ in their orientation relative to the surrounding rock layers.

• Sills are flat intrusions that form between preexisting layers of rock. They are parallel to the bedding of the enclosing rocks, and while they can have various orientations, nearly horizontal sills are most common.1
• Dikes, on the other hand, are tabular bodies that cut across the structure of the country rock, meaning they have a discordant relationship with the surrounding rock layers.2