1. Similarities: 

• Both ionic and metallic crystals have electrostatic forces of attractiàn. 
• In ionic crystals these forces are between oppositely charged ions. In metals,these forces are among the valence electrons and posityely charged kernels. 
• Both have high melting point.

Differences: 

• Ionic bond is strong due to electrostatic forces of attraction whereas metallic bond may be weak or strong depending upon the number of valence electrons and the size of kernels. 
• In ionic bond, ions are not free to move. Hence, they cannot conduct electricity in solid state. They can do so only in molten state or in aqueous solution. ¡n metals, electrons are free to move. Hence, they conduct electricity in solid state.

2. Ionic crystals are hard due to strong electrostatic forces between them. They are brittle because ionic bond is non – directional.